Technology for responding to remarks using speech synthesis

ABSTRACT

The present invention is provided with: a voice input section that receives a remark (a question) via a voice signal; a reply creation section that creates a voice sequence of a reply (response) to the remark; a pitch analysis section that analyzes the pitch of a first segment (e.g., word ending) of the remark; and a voice generation section (a voice synthesis section, etc.) that generates a reply, in the form of voice, represented by the voice sequence. The voice generation section controls the pitch of the entire reply in such a manner that the pitch of a second segment (e.g., word ending) of the reply assumes a predetermined pitch (e.g., five degrees down) with respect to the pitch of the first segment of the remark. Such arrangements can realize synthesis of replying voice capable of giving a natural feel to the user.

TECHNICAL FIELD

The present invention relates to a speech or voice synthesis apparatusand system which, in response to a remark, question or utterance made byvoice input, provide replying output, as well as a coding/decodingdevice related to the voice synthesis.

BACKGROUND ART

In recent years, the following voice synthesis techniques have beenproposed. Examples of such proposed voice synthesis techniques include atechnique that synthesizes and outputs voice corresponding to a speakingtone and voice quality of a user and thereby generates voice in a morehuman-like manner (see, for example, Patent Literature 1), and atechnique that analyzes voice of a user to diagnose psychological andhealth states etc. of the user (see, for example, Patent Literature 2).

Also proposed in recent years is a voice interaction or dialogue systemwhich implements voice interaction with a user by outputting, insynthesized voice, content designated by a scenario while recognizingvoice input by the user (see, for example, Patent Literature 3).

PRIOR ART LITERATURE

Patent Literature 1: Japanese Patent Application Laid-open PublicationNo. 2003-271194

Patent Literature 2: Japanese Patent NO. 4495907

Patent Literature 3: Japanese Patent NO. 4832097

Let's assume a dialogue system which combines the aforementioned voicesynthesis technique and the voice interaction or dialogue system, andwhich searches for data in response to a question given by voice of auser (spoken question by the user) and outputs an answer or reply insynthesized voice. In such a case, however, there would occur a problemthat the voice output by the voice synthesis gives the user an unnaturalfeeling, more specifically a feeling as if a machine were speaking.

SUMMARY OF INVENTION

In view of the foregoing, it is an object of the present invention torealize, in a technique for responding to a question or remark by use ofvoice synthesis, synthesis of responsive or replying voice capable ofgiving a natural feeling to a user. More specifically, the presentinvention seeks to provide a technique which can easily and controllablyrealize replying voice that gives a good impression to the user,replying voice that gives a bad impression, etc.

In studying a man-machine system which synthesizes voice of a reply to aquestion (or remark) given by a user, the inventors of the presentinvention etc. first considered what kinds of dialogues are actuallyconducted between persons, focusing on non-linguistic information (i.e.,non-verbal information other than verbal or linguistic information) andparticularly pitches (frequencies) characterizing dialogues.

Here, consider a dialogue between persons where one of the persons(hereinafter “person b”) returns a reply to a question given by theother person (hereinafter “person a”). Often, in such a case, whenperson a has uttered the question, not only person a but also person b,who is going to reply the question, keeps in mind a pitch of a givensegment of the question with a strong impression. In returning a replyto the question with a meaning of agreement, approval, affirmation orthe like, person b utters replying voice in such a manner that a pitchof a portion characterizing the reply, such as the word ending or wordbeginning, of the reply assumes a predetermined relationship, morespecifically a consonant interval relationship, with (with respect to)the pitch of the question having impressed the person. The inventorsetc. thought that, because the pitch which left an impression in themind of person a about his or her question and the pitch of the portioncharactering the reply of person b are in the above-mentionedrelationship, person a would have a comfortable and easing goodimpression about the reply of person b.

Further, people have communicated with one another for a long time fromthe ancient times when there was no language. It is presumed that pitchand volume of human voice has played a very important role in humancommunications under such environment. It is also presumed that,although voice-pitch-based communications are forgotten in these moderntimes when languages have developed, “predetermined pitch relationship”used from the ancient times can give a “somehow comfortable” feelbecause such a predetermined pitch relationship has been inscribed inthe human DNA and handed down to the present times.

The following describe a specific example of a dialogue between persons.When person a has uttered a question “sou de sho?” in Japanese (meaning“Isn't that right?”), person a and person b generally retain in theirmemories the pitch of “sho” at the word ending of the question where asense of reminder, confirmation or the like is strongly indicated. Insuch a condition, if person b wants to reply affirmatively to thequestion, he or she returns a reply “a, hai” (romanized Japanese meaning“Oh, yes”) in such a manner that the pitch of a portion characterizingthe reply, e.g. the portion “i” (romanized Japanese), assumes theabove-mentioned relationship with the pitch of “sho” (romanizedJapanese) retained in the memories of person a and person b.

FIG. 2 is a diagram showing formants in such an actual dialogue, wherethe horizontal axis represents the time while the vertical axisrepresents the frequency. More specifically, spectra in FIG. 2 indicatea greater intensity as a level of white color increases.

As shown in FIG. 2, the spectra obtained through frequency analyses ofhuman voice appear as a plurality of peaks moving over time, i.e. asformants. More specifically, formants corresponding to “sou de sho?”(romanized Japanese) and formants corresponding to “a, hai” (romanizedJapanese) each appear as three peak zones (i.e., white band-shapedportions moving along the time axis).

Referring now to the first formant of the lowest frequency of the threepeak zones, a frequency depicted at reference character A (i.e.,frequency of a central part in a portion depicted at reference characterA) which corresponds to “sho” in “sou de sho?” (romanized Japanese) isabout 400 Hz, and a frequency of a portion depicted at referencecharacter B which corresponds to “i” in “a, hai” (romanized Japanese) isabout 260 Hz. Thus, it can be seen that the frequency depicted atreference character A is about 3/2 of the frequency depicted atreference character B.

In terms of a musical pitch interval, the relationship where thefrequency ratio is 3/2 refers to an interval from pitch “G” to pitch “C”of the same octave, an interval from pitch “E” to pitch “A” one octavedown from (lower than) the pitch “E” or the like, which is, in otherwords, the relationship of “perfect fifth” as noted later. Such afrequency ratio (i.e., predetermined relationship between pitches) isjust one preferable example, and various other examples of the frequencyratio are also usable in the present invention.

FIG. 3 is a diagram showing relationship between pitch names (syllablenames) and frequencies of human voice, which also shows frequency ratioswith “C” in the fourth octave used as a reference pitch. The frequencyratio of “G” to the reference pitch “C” is 3/2 as noted above. FIG. 3also shows frequency ratios with “A” in the second octave used as areference pitch.

Namely, it can be considered that, in a dialogue between persons, thepitch of a question and the question of a reply are in theaforementioned predetermined relationship instead of being unrelated toeach other. Further, the inventors of the present invention etc.confirmed that the above observation is generally correct, by analyzingmany dialogues and statistically aggregating evaluations performed bymany persons. In studying a dialogue system which outputs a reply to aquestion, uttered by a user, in synthesized voice in the light of theabove observation and confirmation, the inventors of the presentinvention have arranged the voice synthesis in the following manner inorder to achieve the aforementioned objects of the present invention.

Namely, in order to achieve the aforementioned objects, one aspect ofthe present invention provides a voice synthesis apparatus comprising: avoice input section configured to receive a voice signal of a remark; apitch analysis section configured to analyze a pitch of a first segmentof the remark; an acquisition section configured to acquire a reply tothe remark; and a voice generation section configured to generate voiceof the reply acquired by the acquisition section, the voice generationsection controlling a pitch of the voice of the reply in such a mannerthat a second segment of the reply has a pitch associated with the pitchof the first segment analyzed by the pitch analysis section.

According to such an embodiment of the invention, it is possible toprevent the voice of the reply, synthesized in response to the inputvoice signal of a question (remark), from being accompanied by anunnatural feel. Note that the reply to the question (remark) is notlimited to a specific or concrete reply and may sometimes be in the formof back-channel feedback (interjection), such as “ee” (romanizedJapanese meaning “Yah.”), “naruhodo” (“I see.”) or “sou desune” (“Iagree.”) Further, the reply is not limited to one in human voice and maysometimes be in the form of voice of an animal, such as “wan” (“bowwow”)or “Nyâ” (“meow”). Namely, the terms “reply” and “voice” are used hereinto refer to concepts embracing not only voice uttered by a person butalso voice of an animal.

In an embodiment of the present invention, the first segment ispreferably a word ending of the remark (i.e., question), and the secondsegment is preferably a word beginning or word ending of the reply.Because, in many cases, a portion charactering an impression of thequestion is the word ending of the reply, and a portion charactering animpression of the reply is the word beginning or the word ending of thereply.

In an embodiment of the present invention, the voice generation sectionmay be configured to control the pitch of the voice of the reply in sucha manner that an interval of the pitch of the second segment relative tothe pitch of the first segment becomes a consonant interval except for aperfect unison. Here. “consonant” means a relationship where a pluralityof tones having been simultaneously generated mix with one another toharmonize well with each other, and such interval relationships arecalled consonant intervals. The simpler the frequency ratio between twonotes, the higher becomes a degree of consonance. The simplest frequencyratio of 1/1 (perfect unison) and a frequency ratio of 2/1 (perfectoctave) are called absolute consonant intervals, and a frequency ratioof 3/2 (perfect fifth) and a frequency ratio of 4/3 (perfect fourth)plus the above-mentioned frequency ratios of 1/1 (perfect unison) and2/1 (perfect octave) are called perfect consonant intervals. Further,frequency ratios of 5/4 (major third), 6/5 (minor third), 5/3 (majorsixth) and 8/5 (minor sixth) are called imperfect consonant intervals.Further, all the other frequency ratios than the above, such as majorand minor second and seventh and various augmented and diminishedintervals) are called dissonant intervals.

Because it is conceivable that an unnatural feel as a dialogue isinvolved if the word beginning or ending of the reply has the same pitchas the word ending of the question, the perfect prime or unison isexcluded from the relationship between the pitch of the question and thepitch of the reply.

In an embodiment of the present invention, the interval between thepitch of the reply and the pitch of the reply is not limited to aconsonant interval except for a perfect unison and may be any one ofintervals within a predetermined range as below. Namely, the voicegeneration section may be configured to control the pitch of the voiceof the reply in such a manner that an interval of the pitch of thesecond segment relative to the pitch of the first segment becomes anyone of intervals within a predetermined range, except for a perfectunison, that is one octave up and down from the pitch of the firstsegment. If the pitch of the reply is displaced one octave up or downfrom the pitch of the question, not only the consonant intervalrelationship cannot be established, but also the dialogue would becomeunnatural. In this embodiment too, the perfect unison is excluded fromthe pitch relationship within the range one octave up and down from thepitch of the question, because, as noted above, the dialogue may becomeunnatural if the pitch of the reply and the pitch of the question arethe same.

In an embodiment of the present invention, the voice generation sectionmay be configured to control the pitch of the voice of the reply in sucha manner that the interval of the pitch of the second segment relativeto the pitch of the first segment becomes a consonant interval of fivedegrees down from the pitch of the first segment. This arrangementallows the user, having uttered the question, to have a good impressionabout the reply returned to the question.

Further, in an embodiment of the present invention, the voice generationsection may be configured to provisionally set the pitch of the secondsegment of the voice of the reply at the pitch associated with the pitchof the first segment, and the voice generation section may be furtherconfigured to perform at least one of: an operation of, if theprovisionally-set pitch of the second segment is lower than apredetermined first threshold value, changing the provisionally-setpitch to a pitch shifted one octave up; and an operation of, if theprovisionally-set pitch of the second segment is higher than apredetermined second threshold value, changing the provisionally-setpitch to a pitch one octave down. Because, if the provisionally-setpitch of the second segment is lower than the predetermined firstthreshold value (or higher than the predetermined second thresholdvalue), the voice generation section shifts the provisionally-set pitchof the second segment to the pitch one octave up (or down), thisembodiment can prevent voice of the reply from being synthesized atunnaturally too low pitch (or unnaturally too high pitch).

In an embodiment of the present invention, the voice generation sectionmay be configured to provisionally set the pitch of the second segmentof the voice of the reply at the pitch associated with the pitch of thefirst segment, and the voice generation section may be furtherconfigured to change the provisionally-set pitch to a pitch shifted oneoctave up or down in accordance with a designated attribute. Here, the“attribute” is, for example, an attribute of voice to be synthesized,and examples of the attribute include attributes of a female, a child,an adult male, etc. In this case too, the voice generation sectionshifts the provisionally-set pitch of the second segment to the pitchone octave up (or down), and thus, this embodiment can prevent voice ofthe reply from being synthesized at unnaturally too low pitch (orunnaturally too high pitch) in view of the designated attribute.

Further, in an embodiment of the present invention, any one of a firstmode and a second mode is settable as an operation mode of the voicegeneration section. In the first mode, the voice generation section maybe configured to control the pitch of the voice of the reply in such amanner that the interval of the pitch of the second segment relative tothe pitch of the first segment becomes a consonant interval, except fora perfect unison, from the pitch of the first segment. In the secondmode, the voice generation section may be configured to control thepitch of the voice of the reply in such a manner that the interval ofthe pitch of the second segment relative to the pitch of the firstsegment becomes a dissonant interval from the pitch of the firstsegment. In the second mode, voice in the dissonant intervalrelationship with the question (remark) is synthesized, and thus, theembodiment can give an uncomfortable feeling to the user having utteredthe question. Stated conversely, by setting the operation mode of thevoice generation section in the second mode, the embodiment can calluser's attention or intentionally give a threatening feel to the user.On the other hand, by setting the operation mode of the voice generationsection in the first mode, the embodiment permits a consonant intervalrelationship between the question (remark) and the reply (response) andcan thereby give a preferable feeling to the user. Thus, by allowing anyone of the first and second modes to be used properly depending on thecase, the embodiment can significantly enhance the usability of thevoice synthesis apparatus.

When the operation mode of the voice generation section is the firstmode, control may be performed in such a manner that the reply in theconsonant interval relationship except for the perfect unison is outputwith a “pause” (or time interval) within a predetermined time range, inwhich case it is possible to prevent an uncomfortable feeling from beinggiven to the user having uttered the question (remark). Here, a pausewithin the time range of 0.5 sec to 2.0 is considered to be proper.

Generally, in dialogues between persons, a pitch of a question is afactor that characterizes an impression of the question, but theimpression of the question is also greatly influenced by non-linguisticinformation other than the pitch. When a question is uttered by a personwith small voice as in a whisper, an impression that it is requestedimplicitly that a reply to the question be uttered with small voice isgiven to the other party. Further, even when a person remarks “I'm notsad” with a sad expression on his or her face (sad facial expression),the person is considered to be sad non-verbally although the person maysound sad verbally, and thus, an impression that a reply must be made inaccordance with the non-verbal (unspoken) meaning of the remark.Therefore, in studying a dialogue system which outputs a reply to aquestion, uttered by a user, in synthesized voice, not only the pitch ofthe question but also non-verbal information other than the pitch canbecome an important factor in synthesizing the voice of the reply.

Thus, in an embodiment the voice synthesis apparatus of the inventionmay further comprise: a non-linguistic analysis section that analyzesnon-linguistic information, other than pitch, related to the remark; anda control section that controls voice generation, in the voicegeneration section, of the reply in accordance with the analyzednon-linguistic information. Because the voice of the reply (replyingvoice) is controlled by the control section in accordance with thenon-linguistic information, other than pitch, related to the remark(e.g., non-linguistic information, other than pitch, included in theremark, such as volume and speed, or facial expression of the userhaving uttered the remark, it is possible to synthesize replying voiceharmonious with the non-linguistic information, other than pitch,related to the remark. Thus, the present invention can synthesizereplying voice with an unnatural feel.

Note that the reply to be synthesized or generated in accordance withthe present invention may be back-channel feedback (interjection), suchas “ee”, “naruhodo” or “sou desune”, rather than being limited to aspecific reply to the question (remark). Further, examples of thenon-linguistic (non-verbal) information, other than pitch, in a questioninclude facial expression, gesture, clothes, etc. of the user havinguttered the question in addition to information related to the voice ofthe question like volume, voice quality and speed (speaking speed).

By the way, whereas a pitch of a question in a dialogue between personsis a factor that characterizes an impression of the question as notedabove, it has been recognized empirically that a way of replying(responding) differs depending on the verbal or linguistic content ofthe question and the reply (response). For example, if a reply “Yes(hai)” is to be returned, the reply is returned to the questionrelatively quickly, but, if a reply “No (iie)” is to be returned, thereply is returned to the question with a little pause (time interval) inconsideration of an impression that will be given to the other party inthe dialogue. Therefore, in studying a dialogue system which outputs areply to a question (remark), uttered by a user, in synthesized voice,the verbal or linguistic meaning of the question (remark) and the reply(response) too can become an important factor in synthesizing the voiceof the reply.

In view of the foregoing, an embodiment of the present invention mayfurther comprise: a linguistic analysis section that analyzes linguisticinformation included in the remark and the reply; and a control sectionthat controls voice generation, in the voice generation section, of thereply in accordance with the analyzed linguistic information. Becausethe synthesis of the replying voice is controlled in accordance with thelinguistic information included in the remark (question) and the reply(response), an impression as if a dialogue were being conducted with aperson, although the replying voice is machine-synthesized voice. Notethat one example form of controlling the synthesis of the voice of thereply (response) itself in accordance with the linguistic informationinclude in the reply (response) as above may comprise controlling thevoice of the reply (response) in accordance with whether the reply(response) has an affirmative meaning or a negative meaning.

By the way, it has been recognized empirically that the way of replying(responding) differs depending, for example, on a manner of pitchvariation over time, rather than the pitch itself alone, in the remark.For example, even where a voiced remark ends with a noun like “asu wahare” (romanized Japanese meaning “Will it be fine tomorrow?”), it canbecome a question (interrogative sentence) meaning “asu wa hare desuka?”(“Will it be fine tomorrow?”) if the pitch rises toward the word ending.If the pitch is substantially constant in the remark “asu wa hare”, thisremark should be a kind of mere monologue or mutter. Thus, a reply(back-channel feedback) like “so desune” responsive to the remark willalso be substantially constant in pitch. Therefore, in studying adialogue system which returns a reply to a remark, uttered by a user, insynthesized voice, not only the pitch of the remark but also thenon-verbal or non-linguistic information indicative of a manner of pitchvariation of the remark can become an important factor in synthesizingthe voice of the reply.

In view of the foregoing, one embodiment of the present invention mayfurther comprise: a non-linguistic analysis section that analyzes pitchvariation in the remark; and a control section that controls a pitch ofvoice of the reply, generated in the voice generation section, to varyin accordance with the pitch variation in the remark. Because the pitchvariation in the reply is controlled in accordance with the pitchvariation over time in the remark, an impression as if a dialogue werebeing conducted with a person can be given to the user, although thevoice of the reply (replying voice) is machine-synthesized voice. Notethat one example form of controlling the pitch of the voice of the replyin accordance with the manner of pitch variation in the remark as abovemay comprise making flat the reply as back-channel feedback if there isalmost no pitch variation over time in the remark (i.e., if the pitch inthe remark is flat). Further, if the remark is an interrogative sentencewhere the pitch rises toward the word ending, one example form ofcontrolling the pitch of the voice of the reply in accordance with themanner of pitch variation in the remark may comprise lowering the pitchof the reply toward the word ending.

By the way, in studying a dialogue system which returns a reply to aremark, uttered by a user, in synthesized voice, it is conceivable thatpersons of various attributes, irrespective of sex and age, become usersof the dialogue system. Further, there are typical models in data, suchas voice fragments, that are to be used in voice synthesis. Statedconversely, voice of replies can be synthesized with various voicequality as long as a plurality of models are prepared in advance for usein voice synthesis. Thus, where replies are to be output through voicesynthesis (i.e., in synthesized voice), the replies can be output withvarious attributes (agent attributes). Therefore, in the dialoguesystem, it must be taken into consideration that there are a variety ofcombinations of attributes of users (utterers' or speakers' attributes)and agent attributes. More specifically, in a case where an utterer orspeaker of a remark is a female and a replier is a male, and if the maleattempts to reply to the remark in such a manner that the pitch of theword ending or the like of the reply to the remark assumes apredetermined relationship with the pitch of the word ending of thefemale's remark, the pitch of the word ending or the like of the replywould be too high for the male, so that the reply would undesirablybecome unnatural. Conversely, in a case where the utterer or speaker ofa remark is a male and the replier is a female, and if the femaleattempts to reply to the remark in such a manner that the pitch of theword ending or the like of the reply to the remark assumes apredetermined relationship with the pitch of the word ending of themale's remark, the pitch of the word ending or the like of the replywould be too low for the female.

In view of the foregoing, an embodiment of the present invention isproposed, in which the voice generation section may be configured toassociate the pitch of the second segment with the pitch of the firstsegment in accordance with a given rule and generate voice with acharacteristic based on a given agent attribute, and the embodiment mayfurther comprise a control section that determines the rule based on atleast one the agent attribute and an attribute of a speaker of theremark.

According to the embodiment, the rule for associating the pitch of thesecond segment with the pitch of the first segment is determined on thebasis of the attribute of a speaker of the remark or the agentattribute. Thus, a pitch characteristic of the voice of the reply thatis controlled in pitch in accordance with the determined rule will bevariably controlled in accordance with at least one of the attribute ofthe speaker of the remark and the agent attribute. Thus, although thevoice of the reply to the remark is machine-synthesized voice, a naturaldialogue feel can be given to the user, and a kind of delight can begiven to the user about conducting a dialogue using the voice synthesisapparatus of the invention.

The agent attribute is an attribute of a model to be used forsynthesizing voice, such as a sex or age. As an example, one or aplurality of agent attributes are preset in the voice synthesisapparatus, so that any one of the agent attributes can be selected orset for use in synthesis of voice as appropriate. Further, the attributeof the speaker of the remark is the sex of the speaker, such as male,female or neutral. Further, examples of the attribute of the speaker ofthe remark may include, in addition to the sex, the age, and thegeneration like child generation, adult generation and aged mangeneration. Such an attribute of the speaker may be indicated to thevoice synthesis apparatus in advance as the remark is input to the voicesynthesis apparatus, or may be automatically identified by the voicesynthesis apparatus analyzing a voice signal of the received remark.

Even where an attempt is made to find, on the basis of statistics, pitchrelationships which people can feel comfortable etc., such pitchrelationships which people can feel comfortable etc. differ from oneperson to another, and thus, there are limitations to obtainingpreferable rules only through statistical analyses. Further, in adialogue system which returns a reply to a remark, uttered by aparticular user, in synthesized voice, it is important to increase thenumber and frequency of remarks of the particular user, or simply put,liven up a dialogue between the particular user and the machine.

In view of the foregoing, an embodiment of the present invention isproposed, in which the voice generation section may be configured toassociate the pitch of the second segment with the analyzed pitch of thefirst segment in accordance with a given rule and generate voice with acharacteristic based on a given agent attribute, and the embodiment mayfurther comprise a control section that updates the rule based onreceiving voice of a further remark via the sound input section aftersounding of the voice of the reply. The above-mentioned rule forassociating the pitch of the second segment of the reply with theanalyzed pitch of the first segment is updated based on receiving thevoice of the further remark via the sound input section after generationor sounding of the voice of the remark. Namely, the rule to be appliedto sounding or generation of voice of the next reply is updated asappropriate in consideration of the further remark uttered by the userin response to the machine-synthesized reply. This rule-updating featurecan direct the dialogue in a livelier direction.

The aforementioned embodiment may be configured so that theabove-mentioned rule is set in accordance with any one of a plurality ofpreset scenes. Here, examples of the scenes include combinations ofsexes and ages of speakers and sexes and ages of voice to besynthesized, combinations of speeds (rapid utterance and slow utterance)of remarks and speeds of replies whose voice is to be synthesized,purposes of dialogues (such as voice guidance), etc.

In a typical dialogue between persons, one of the persons (person a)utters a remark, and the other person (person b) utters a remark inresponse to the remark of person a. However, the remark of person bresponsive to the remark of person a is not always a reply in the formof a specific sentence and may sometimes be in the form of mereback-channel feedback like “a, hai”, “sou desune”, “sorede” or the like.Further, it is well known empirically that, in the dialogue betweenpersons, such back-channel feedback is returned to the remark of persona promptly with a good response. Thus, in studying a dialogue systemwhich returns a reply to a remark, uttered by a user, in synthesizedvoice, it is important to allow back-channel feedback to be output as asimple reply promptly with a good response.

In view of the foregoing, a coding/decoding device according to anotheraspect of the present invention comprises: an A/D converter thatconverts an input voice signal of a remark into a digital signal; apitch analysis section that analyzes a pitch of a first segment of theremark based on the digital signal; a back-channel feedback acquisitionsection that, when back-channel feedback is to be returned to theremark, acquires back-channel feedback data corresponding to a meaningof the remark, a pitch control section that controls a pitch of theback-channel feedback data in such a manner that a second segment of theback-channel feedback data has a pitch associated with the analyzedpitch of the first segment; and a D/A converter configured to convertthe pitch-controlled back-channel feedback data into an analogue signal.Such arrangements can provide a compact coding/decoding device which iscapable of realizing a man-machine dialogue function and which isconfigured in such a manner that the remark input as an analogue signalis processed after being converted into a digital signal, voice data ofback-channel feedback corresponding to the meaning of the remark iscreated digitally, and an analogue back-channel feedback voice signal isultimately output. In this way, back-channel feedback can be createdpromptly with a good response, and it is possible to prevent anunnatural feeling from accompanying synthesized voice of theback-channel feedback.

According to still another aspect of the present invention, there isprovided a voice synthesis system comprising a coding/decoding deviceand a host computer. Here, the coding/decoding device comprises: an A/Dconverter that converts an input voice signal of a remark into a digitalsignal; a pitch analysis section that analyzes a pitch of a firstsegment of the remark based on the digital signal; a back-channelfeedback acquisition section that, when back-channel feedback is to bereturned to the remark, acquires back-channel feedback datacorresponding to a meaning of the remark; a pitch control section thatcontrols a pitch of the back-channel feedback data in such a manner thata second segment of the back-channel feedback data has a pitchassociated with the analyzed pitch of the first segment; and a D/Aconverter configured to convert the pitch-controlled back-channelfeedback data into an analogue signal. The host computer is configuredin such a manner that, when replying voice other than the back-channelfeedback is to be returned to the remark, the host computer acquiresreplying voice data, responsive to the remark, in accordance with thedigital signal converted by the A/D converter and returns the acquiredreplying voice data to the coding/decoding device, the pitch controlsection is further configured to control a pitch of the replying voicedata in such a manner that a third segment of the received replyingvoice data has a pitch associated with the analyzed pitch of the firstsegment, and the D/A converter is further configured to convert thepitch-controlled replying voice data, into an analogue signal.

Thus, voice of back-channel feedback (simple reply) responsive to theinput remark can be generated efficiently through prompt processing bythe coding/decoding device, while voice of a reply having a relativelycomplicated linguistic meaning responsive to the input remark can begenerated efficiently through large-capacity centralized processing bythe host computer, so that there can be provided a voice synthesissystem capable of realizing a flexible man-machine dialogue function.

The present invention may be embodied only as the voice synthesisapparatus or system or the coding/invention device discussed above butalso as a method implemented by a computer or processor. Also, thepresent invention may be embodied as a non-transitory computer-readablestorage medium storing a software program comprising a group ofinstructions for causing a computer or processor to function as thevoice synthesis apparatus.

In the present invention, pitch (frequency) of a question is an objectof analysis while pitch of a reply is an object of control, as discussedabove and below. However, as apparent from the above-discussed examplesof formants, human voice has certain frequency bands, and thus, humanvoice would unavoidably present errors within a certain frequency rangein the analysis and control as well. Besides, errors inevitably occur inanalyses and control. Therefore, according to the present invention, itis allowed that, for the analysis and control, human voice accompanieserrors within a certain range, instead of being constant in pitch(frequency) values.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a construction of a first embodimentof a voice synthesis apparatus of the present invention;

FIG. 2 is a diagram showing an example of formants of voice in adialogue;

FIG. 3 is a diagram showing relationship between pitch names andfrequencies etc.;

FIG. 4 is a flow chart showing processing performed by the firstembodiment of the voice synthesis apparatus;

FIGS. 5(a) and 5(b) are diagrams showing an example specific manner inwhich a word ending is identified;

FIGS. 6(a), 6(b), 6(c), 6(d), 6(e) and 6(f) are diagrams showingexamples of pitch shift operations performed on a voice sequence;

FIGS. 7(a), 7(b), and 7(c) are diagrams showing psychologicalimpressions which voice synthesis gives to a user's remark;

FIG. 8 is a block diagram showing a construction of a second embodimentof a voice synthesis apparatus of the present invention;

FIGS. 9(a) and 9(b) are diagrams showing an example manner in whichpitch conversion is performed on voice waveform data;

FIG. 10 is a flow chart showing primary portions of a process inApplication Example 1;

FIG. 11 is a flow chart showing primary portions of a process inApplication Example 2;

FIG. 12 is a flow chart showing primary portions of a process inApplication Example 3;

FIGS. 13(a) and 13(b) provide a flow chart showing prinary portions of aprocess in Application Example 4;

FIG. 14 is a block diagram showing a construction of a third embodimentof the voice synthesis apparatus;

FIG. 15 is a flow chart of a process performed in the third embodimentof the voice synthesis apparatus;

FIG. 16 is a block diagram showing a construction of a fourth embodimentof the voice synthesis apparatus of the present invention;

FIGS. 17(a) and 17(b) are diagrams explanatory of voice synthesis in afifth embodiment of the present invention;

FIG. 18 is a flow chart showing primary portions of a process performedin a sixth embodiment of the voice synthesis apparatus of the presentinvention;

FIG. 19 is a block diagram showing a construction of a seventhembodiment of the voice synthesis apparatus of the present invention;

FIG. 20 is a block diagram showing a construction of an eighthembodiment of the voice synthesis apparatus of the present invention;

FIG. 21 is a flow chart showing an operational sequence executed by aneighth embodiment of the voice synthesis apparatus;

FIGS. 22(a) and 22(b) are diagrams showing an example of a pitch shiftoperation performed on a voice sequence;

FIGS. 23(a) and 23(b) are diagrams showing an example of a pitch shiftoperation performed on a voice sequence;

FIGS. 24(a) and 24(b) are diagrams showing an example of a pitch shiftoperation performed on a voice sequence;

FIG. 25 is a diagram explanatory of output timing of a reply;

FIG. 26 is a diagram explanatory of output timing of a reply;

FIG. 27 is a block diagram showing a construction of a ninth embodimentof the voice synthesis apparatus of the present invention;

FIG. 28 is a flow chart of voice synthesis processing performed in theninth embodiment of the voice synthesis apparatus;

FIGS. 29(a) and 29(b) are diagrams showing a particular specific examplemanner in which a word ending and pitch variation are identified;

FIGS. 30(a) and 30(b) are diagrams showing an example of a pitch shiftoperation performed on a voice sequence;

FIGS. 31(a) and 31(b) are diagrams showing an example of a pitch shiftoperation performed on a voice sequence;

FIG. 32 is a block diagram showing a construction of a modification ofthe voice synthesis apparatus of the present invention;

FIG. 33 is a block diagram showing a construction of a tenth embodimentof the voice synthesis apparatus of the present invention;

FIG. 34 is a flow chart of voice synthesis processing performed in thetenth embodiment of the voice synthesis apparatus;

FIG. 35 is a flow chart showing details of a rule determination processin the voice synthesis processing of FIG. 34;

FIGS. 36(a) and 36(b) are diagrams showing an example of a pitch shiftoperation performed on a voice sequence;

FIG. 37 is a diagram showing an example of a pitch shift operationperformed on a voice sequence;

FIG. 38 is a diagram showing an example of a pitch shift operationperformed on a voice sequence;

FIG. 39 is a diagram showing an example of a pitch shift operationperformed on a voice sequence;

FIG. 40 is a diagram showing an example of a pitch shift operationperformed on a voice sequence;

FIG. 41 is a block diagram showing a construction of an eleventhembodiment of the voice synthesis apparatus of the present invention;

FIG. 42 is a diagram showing an example of an index table in theeleventh embodiment of the voice synthesis apparatus;

FIG. 43 is a diagram showing an example switching in an operation periodin the eleventh embodiment of the voice synthesis apparatus; FIG. 44 isa flow chart of voice synthesis processing performed in the eleventhembodiment of the voice synthesis apparatus;

FIG. 45 is a flow chart showing a table update process performed in theeleventh embodiment of the voice synthesis apparatus;

FIG. 46 is a diagram showing an example of an index table in a twelfthembodiment of the voice synthesis apparatus;

FIGS. 47(a), 47(b), 47(c), and 47(d) are diagrams showing examples ofindex tables in a thirteenth embodiment of the voice synthesisapparatus;

FIG. 48 is a diagram showing a hardware setup of a voice synthesisapparatus constructed in accordance with a fourteenth embodiment of thepresent invention;

FIG. 49 is a functional block diagram showing functional arrangements ofthe voice synthesis apparatus in accordance with the fourteenthembodiment;

FIG. 50 is a flow chart of voice processing performed in the voicesynthesis apparatus of FIG. 49;

FIG. 51 is a flow chart showing details of a back-channel feedbackprocess in the voice processing of FIG. 50; and

FIG. 52 is a flow chart showing details of a reply process in the voiceprocessing of FIG. 50.

DESCRIPTION OF EMBODIMENTS

Now, preferred embodiments of the present invention will hereinafter bedescribed in detail with reference to the accompanying drawings.

<First Embodiment>

First of all, a first embodiment of a voice synthesis apparatus of thepresent invention will be described. FIG. 1 is a block diagram showing aconstruction of the first embodiment of the voice synthesis apparatus 10of the present invention. In FIG. 1, the voice synthesis apparatus 10 isa terminal apparatus, such as a mobile or portable apparatus, includinga CPU (Central Processing Unit), a voice input section 102, and aspeaker 142. In the voice synthesis apparatus 10, a plurality offunctional blocks are built as follows by the CPU executing apreinstalled application program.

More specifically, in the tone synthesis apparatus 10 are built avoice-utterance-section detection section 104, a pitch analysis section106, a linguistic analysis section 108, a reply creation section 110, avoice synthesis section 112, a linguistic database 122, a reply database124, an information acquisition section 126 and a voice library 128.Namely, each of the functional blocks in the illustrated voice synthesissection 10 is implemented through cooperation between a program modulecorresponding to the functional block and the CPU. However, as obviousto persons skilled in the art, at least some of the functional blocksmay be implemented by a DSP (Digital Signal Processor) or by a discretehardware circuit section.

Although not particularly shown, the tone synthesis apparatus 10 furtherincludes a display section, an operation input section, etc. so that auser can check states of the apparatus and input various operations tothe apparatus. Further, the voice synthesis apparatus 10 may be anotebook-type or tablet-type personal computer rather than a terminalapparatus, such as a portable phone.

As will be detailed later, the voice input section 102 comprises: amicrophone that converts a voice input by the user into an electricalvoice signal; an LPF (Low Pass Filter) that cuts off high frequencycomponents of the converted voice signal; and an A/D converter thatconverts the voice signal, having the high-frequency components cut offtherefrom, into a digital signal. Thus, the voice input section 102 isconstructed to receive an input voice signal of a question or remarkuttered by the user. The voice-utterance-section detection section 104detects a voice utterance section by processing the voice signalconverted into the digital signal.

The pitch analysis section 106 performs frequency analysis on the voicesignal detected as the voice utterance section. Of a first formantobtained through the frequency analysis, the pitch analysis section 106obtains a pitch of a particular segment (first segment) of the voicesignal and outputs pitch data indicative of the obtained pitch. Notethat the first segment here is, for example, the word ending of aquestion (or remark), and that the first formant is one of a pluralityof formants, obtained for example through the frequency analysis of thevoice, which is the lowest in frequency; in the illustrated example ofFIG. 2, the first formant is a peak zone whose end is indicated byreference character “A”. For the frequency analysis, the FFT (FastFourier Transform) or any other desired conventionally-known method maybe employed. A specific technique for identifying the word ending of aquestion (or remark) will be described in detail later.

The linguistic analysis section 108 determines, with reference tophoneme models prestored in the linguistic database 122, which phonemethe detected voice signal detected as the voice utterance section isclosest to, and thereby analyzes (identifies) a meaning of words definedby the voice signal. Note that the hidden Markov models can be used asphoneme models.

The reply creation section 110 creates a reply corresponding to themeaning identified by the linguistic analysis section 108, withreference to the reply database 124 and the information acquisitionsection 126. For example, in response to a question (or a remark) “Whattime is it now?”, the voice synthesis section 10 acquires timeinformation from a built-in realtime clock (not shown) and otherinformation than the time information from the reply database 124. Inthis manner, the reply creation section 110 can create a reply(response) “It is xx hours and xx minutes”.

In response to a question “ashita no tenki wa” (romanized Japanesemeaning “How will the weather be tomorrow?”), on the other hand, thevoice synthesis section 10 is unable to create a reply unless itaccesses an external server to acquire weather information. Namely, theinformation acquisition section 126 is constructed or configured toaccess the external serer via the Internet to acquire informationnecessary for creation of the reply if the voice synthesis apparatus 10cannot create the reply. Namely, the reply creation section 110 isconstructed or configured to acquire, from the reply database 124 or theexternal server, a reply (response) to the question. In theaforementioned manner, a combination of the reply creation section 110,the reply database 124, the information acquisition section 126, etc.functions as an acquisition section constructed to acquire a reply tothe remark.

In the instant embodiment, the reply creation section 110 outputs areply as a phoneme train that is a voice sequence defining pitches andgeneration timing of individual phonemes. By the voice synthesis section112 synthesizing voice in accordance with such a voice sequence definingpitches and generation timing of individual phonemes, fundamental voiceof the reply can be output. However, in the instant embodiment, thefundamental voice, defined by the voice sequence, is output after thevoice synthesis section 112 changing the fundamental voice.

The voice synthesis section 112 performs voice synthesis by changing thepitches of the entire voice sequence in such a manner that the pitch ofa particular segment (second segment) of the replying voice sequencecreated by the reply creation section 110 assumes a predeterminedinterval relationship with pitch data of the first segment supplied fromthe pitch analysis section 106, and then, the voice synthesis section112 outputs the synthesized voice as a replying voice signal. Note that,whereas the second segment is described as a segment constituting theword ending of the reply, it is not limited to such a word ending of thereply as will be described later. Further, whereas the pitch having thepredetermined interval relationship with the pitch data of the firstsegment is described as a pitch five degrees down from (lower than) thepitch represented by the pitch data, it may be a pitch having arelationship other than five degrees down from the pitch represented bythe pitch data. In any case, the voice synthesis section 112 functionsas a voice generation section not only constructed to generate voice ofthe acquired reply but also constructed to control the pitch of thereplying voice to have a pitch associated with the pitch of the analyzedfirst segment.

In synthesizing voice, the voice synthesis section 112 uses voicefragment data registered in the voice library 128. The voice library 128is a database having preregistered therein voice fragment data definingwaveforms of various voice fragments, such as individual phonemes andphoneme-to-phoneme transition portions, that are to be used as materialsof voice. More specifically, the voice synthesis section 112 generates avoice signal by combining voice fragment data of individual sounds(phonemes) of a voice sequence, modifying connection portions betweenthe sounds (phonemes) and changing the pitch of the word ending of thereply. Note that the voice signal thus generated by the voice synthesissection 112 is converted into an analog signal by a not-shown D/Aconversion section and then audibly output through the speaker 142.

The following describe behavior of the voice synthesis apparatus 10,with reference to FIG. 4 that is a flow chart showing processingperformed by the voice synthesis apparatus 10. First, once the userperforms a predetermined operation, e.g. once the user selects, on amain menu, an icon or the like corresponding to a dialogue process, theCPU activates an application program corresponding to the process. Byactivating the application program, the CPU builds the functions of thevarious sections shown in the block diagram shown in FIG. 1.

First, at step Sa11, the user inputs a question or remark in vocal formto the voice input section 102, and the voice input section 102 receivesthe input voice signal. Then, at step Sa12, theutterance-section-detection section 104 detects, as a silent section, asection of the input voice signal where a zero intensity state, i.e.zero volume state, of the voice continues for more than a predeterminedtime period and detects the other section of the input voice signal as avoice utterance section, and then the voice-utterance-section detectionsection 104 supplies the voice signal of the voice utterance section tothe pitch analysis section 106 and the linguistic analysis section 108.

Then, at step Sa13, the pitch analysis section 106 analyzes the voicesignal, in the detected utterance section, of the question (or remark),identifies a pitch of the first segment (word ending) in the question(or remark), and then supplies pitch data indicative of the identifiedpitch to the voice synthesis section 112. The following describe anexample of a specific method for identifying the word end in thequestion (or remark) by means of the pitch analysis section 106.

Assuming a dialogue where a person giving a question (or remark) wants areply to the question (or remark), it is considered that a portion ofthe question (or renark) that constitutes to the word ending willtemporarily become large in volume as compared to the other portions.Thus, a pitch of the first segment (word ending) can be identified, forexample, in the following manner.

First, the pitch analysis section 106 converts a voice signal of thequestion (or remark), detected as an utterance section, into waveformsseparately for the volume and pitch of the question (or remark). FIG.5(a) shows an example of the volume waveform of the voice signal, wherethe vertical axis represents the volume of the voice signal while thehorizontal axis represents the elapsed time. FIG. 5(b) shows an exampleof the pitch waveform of the voice signal, where the vertical axisrepresents the pitch of the first formant obtained through frequencyanalysis of the same voice signal while the horizontal axis the elapsedtime. Note that the time axis is the same between the volume waveform ofFIG. 5(a) and the pitch waveform of FIG. 5(b). As shown, the volumewaveform has a plurality of local maximums (local peaks).

Second, the pitch analysis section 106 identifies a time of thetemporally last local peak P1 of the volume waveform of FIG. 5(a).

Third, the pitch analysis section 106 identifies, as the word ending, apredetermined time range (e.g., 100 μsec-300 μsec) before and after theidentified time of the local peak P1.

Fourth, the pitch analysis section 106 extracts and outputs, as pitchdata of the first segment, an average pitch of a segment Q1corresponding to the identified word ending of the utterance of thepitch waveform shown in FIG. 5(b).

It is considered that identifying the last local peak P1 of the volumewaveform in the utterance section as the time corresponding to the wordending of the question (or remark) as above can reduce erroneousdetection of the word ending of the question in the dialogue.

Whereas the predetermined time range before and after the temporallylast local peak P1 in the volume waveform shown in FIG. 5(a) has beendescribed as being the word ending, a predetermined time range havingthe local peak P1 as its start or end time point may be identified asthe word ending. Further, a pitch at the start or end time point of thesegment Q1 or at the local peak P1, rather than the average pitch of thesegment Q1 corresponding to the identified word ending, may be extractedand output as the pitch data of the first segment.

Meanwhile, at step Sa14, the linguistic analysis section 108 analyzes ameaning of words in the input voice signal and supplies the replycreation section 110 with data indicative of the meaning of the words.Then, at step Sa15, the reply creation section 110 acquires a replyinglinguistic data train by creating appropriate replying wordscorresponding to the analyzed meaning of the words by use of the replydatabase 124 or acquiring such appropriate replying words from anexternal server via the information acquisition section 126 asnecessary, then creates a voice sequence (replying voice sequence) onthe basis of the acquired linguistic data train, and then supplies thecreated voice sequence to the voice synthesis section 112.

FIG. 6(a) is a diagram showing, in a staff notation, an examplefundamental pitch variation in a replying voice sequence in Japanesecreated in response to a question (remark) of “ashita no tenki wa”(romanized Japanese meaning “How will the weather be tomorrow?”). In theillustrated example of FIG. 6(a), a note is allocated to each of sounds(syllables) in a reply “hare desu” (romanized Japanese meaning “It willbe fine tomorrow.”), so as to indicate pitches and generation timing ofindividual words (syllables or phonemes) of fundamental voice defined bythe voice sequence. Although one note is allocated to each of the sounds(syllables or phonemes) in the illustrated example of FIG. 6(a) forsimplicity of explanation, a plurality of notes may be allocated to agiven one of the sounds by use of a note-connecting symbol, such as aslur or glissando, a plurality of sounds of different pitches may beinterconnected transiently, etc. (see for example FIG. 6(c)).

Next, at step Sa16, the voice synthesis section 112 identifies a pitch(initial pitch) of a predetermined second segment (the word ending ofthe utterance in this case) in the replying voice sequence supplied fromthe reply creation section 110. For example, in FIG. 6(a), the notedepicted by reference character “B” indicates a pitch (initial pitch) ofa segment “su” (romanized Japanese) at the word ending (second segment)in a reply “hare desu”; in the illustrated example of FIG. 6(a), thepitch of the second segment is “F”. Extraction of the second segment(word ending in the illustrated example) from the acquired replyingvoice sequence may be performed by any suitable scheme. For example,because the individual syllables in the replying voice sequence can bedistinguished from one another, the segment of the last syllable may beextracted as the second segment (word ending).

Then, at step Sa17, the voice synthesis section 112 changes the pitchesdefined in the voice sequence in such a manner that the initial pitch ofthe word ending defined in the voice sequence assumes an intervalrelationship of five degrees up from (lower than) the pitch indicated bythe pitch data supplied from the pitch analysis section 106.

FIG. 6(b) is a diagram showing, in a staff notation, an example ofreplying voice “hare desu” (romanized Japanese) having beenpitch-shifted to be five degrees down from (lower than) the pitchesshown in FIG. 6(a). In FIG. 6(b), a note depicted by reference character“A” indicates an example pitch of a segment (first segment) of “wa”(romanized Japanese) at the word ending of a question “ashita no tenkiwa?” (romanized Japanese); in the illustrated example, the pitch of theword ending of the question is “G”. In this case, the voice synthesissection 112 shifts the pitches in the entire voice sequence in such amanner that the pitch of the segment of “su” at the word ending,depicted by reference character “B”, in the reply “hare desu” (romanizedJapanese) is changed to “C” that is five degrees down from (lower than)the pitch “G”.

Then, at step Sa18, the voice synthesis section 12 synthesizes the voiceof the thus-changed voice sequence and outputs the synthesized voice.Although not particularly shown, once the voice of the reply (replyingvoice) is output, the CPU terminates the execution of the instantapplication program and returns to a menu screen.

The pitch variation pattern (note pattern) of the replying voicesequence is not limited to the ones shown in FIG. 6(a) and FIG. 6(b),and any other pitch variation pattern may be set as desired. FIG. 6(c)and FIG. 6(d) show examples where the same linguistic data train of“hare desu” (romanized Japanese) is sounded in a pitch variation patterndifferent from those shown in FIG. 6(a) and FIG. 6(b).

FIG. 6(a) to FIG. 6(d) show example replies in Japanese. Needless tosay, if the type of the language used for the reply differs, the voicecompletely differs and hence the pitch variation pattern (note pattern)including intonations and accents differs, although the meaning of thereply is the same. Thus, an example replying voice will be discussedbelow for several different types of languages. FIG. 6(e) shows, in astaff notation, an example pitch variation pattern (note pattern) havingbeen subjected to pitch shifting in a case where the reply of “haredesu” is made in English (i.e., “It'll be fine.”). FIG. 6(f) shows, in astaff notation, an example pitch variation pattern (note pattern) havingbeen subjected to pitch shifting in a case where the reply of “haredesu” is made in Chinese.

FIG. 7 is a diagram explanatory of various impressions which theembodiment of the voice synthesis apparatus 10 gives a user. As shown inFIG. 7(a), the user W inputs a question “ashita no tenki wa?” (romanizedJapanese) to the voice synthesis apparatus 10 that is a terminalapparatus. If a pitch of“wa” that constitutes the word ending of thequestion is “G”, voice of a voice sequence “hare desu” (romanizedJapanese) constituting a reply to the question is synthesized in theinstant embodiment with the pitches shifted so that the pitch of “su”(romanized Japanese) at the word ending of the reply becomes “C”, asshown in FIG. 7(c). In this manner, the instant embodiment can give theuser W a good impression as if a dialogue were being actually conducted,without giving the user an unnatural feel.

If, on the other hand, the voice of the voice sequence “hare desu”(romanized Japanese) is synthesized without the pitches being shifted(see FIG. 6(a)), then “su” (romanized Japanese) at the word ending ofthe reply is output with the pitch “F”, as shown in FIG. 7(c). In thiscase, the pitch “F” is in a dissonant interval relationship with thepitch “G” of “wa” (romanized Japanese) that constitutes the word endingof the question “ashita no tenki wa?” (romanized Japanese). Namely, asseen in FIG. 3, the frequency of the pitch “G” that is 396.0 Hz is in a9/8 relationship with the frequency of the “F” that is 352.0 Hz. Thus, abad impression like disgust, rather than an unnatural feel, would begiven to the user W. Note, however, that the voice synthesis apparatus10 may be configured to positively give such a bad impression to theuser.

<Second Embodiment>

The following describe a second embodiment of the voice synthesisapparatus 10 of the present invention, which employs a modification ofthe replying voice generation method. FIG. 8 is a block diagram showinga construction of the second embodiment of the voice synthesis apparatus10 of the present invention. Whereas the above-described firstembodiment is constructed in such a manner that the reply creationsection 110 outputs a voice sequence where a pitch is allocated persound (syllable) of a replying language responsive to a question andthat the voice synthesis section 112 synthesizes voice of a reply(replying voice) on the basis of the voice sequence, the secondembodiment is constructed in such a manner that the replying voiceoutput section 113 acquires a reply (response) to a question (remark)and generates and outputs voice waveform data of the entire reply(response).

Examples of the above-mentioned reply (response) include one created bythe replying voice output section 113, one acquired from an externalserver, one selected from among a plurality of replies prepared inadvance. Further, the above-mentioned voice waveform data is, forexample, data in the WAV format, where each sound (syllable) is notdivided from the other sounds (syllables) as divided in theaforementioned voice sequence; namely, no pitch is explicitly allocatedper syllable. FIG. 9(a) shows an example pitch variation pattern of suchreplying voice waveform data, which corresponds to fundamental voice asin FIG. 6(a). Thus, if the voice waveform data comprising suchfundamental voice is simply reproduced, the reproduced voice waveformdata would not appropriately correspond to a pitch variation of thequestion (remark or utterance input) and would give a mechanical feel.In view of this, the second embodiment is constructed to control thepitches of the voice waveform data in accordance with the pitchvariation of the question (remark or utterance input), as in the firstembodiment. For that purpose, a post-processing section 114 is providedin the second embodiment.

The post-processing section 114 performs control to change the pitchesof the entire voice waveform data of the replying voice in such a mannerthat the pitch of the word ending of the reply (responsive output)assumes a predetermined interval relationship (e.g., consonant intervalrelationship) with the pitch of the word ending of the question(utterance input). More specifically, the post-processing section 114analyzes the pitch (initial pitch) at the word ending (second segment)in the replying voice waveform data (fundamental voice) output from thereplying voice output section 113, and then the post-processing section114 performs pitch conversion on the entire voice waveform data(fundamental voice) output from the replying voice output section 113 insuch a manner that the pitch of the word ending (second segment) assumesa predetermined interval relationship with, e.g. five degrees down from(lower than), the pitch of the word ending (second segment) of the inputvoice supplied from the pitch analysis section 106. Namely, thepost-processing section 114 changes the pitch of the word ending of theacquired reply (response) so as to be five degrees down from the pitchof the word ending of the question (remark) that is an example consonantinterval relationship with the pitch of the word ending of the question(remark). As shown in FIG. 9(b), a result of the pitch conversion issubstantially similar to the result of the pitch shift shown in FIG.6(b). Note that, to analyze the pitch (initial pitch) at the word ending(second segment) in the replying voice waveform data, thepost-processing section 114 may use a method similar to the methoddescribed above with reference to FIG. 5. Namely, the post-processingsection 114 may analyze the volume of the replying voice waveform datato detect the last local maximum (local peak) and identify as the wordending (second segment) a suitable time range containing the last localmaximum.

Because the second embodiment constructed as above does not include amechanism for performing complicated voice syntheses like the voicesynthesis section 112, it is well suited for application to cases wherewords of replying voice are not complicated (e.g., to a reply comprisingsimple back-channel feedback). Namely, where a reply to a question neednot be so complicated or specific, e.g., where a reply to a question ismade with a simple reply like “hai” (“Yes”) or “iie” (“No”) orback-channel feedback like “sou desune” (“I agree.”), the replying voiceoutput section 113 only has to select and output, from among a pluralityof prestored voice waveform data, voice waveform data suitable to thequestion, with the result that the voice synthesis apparatus can besimplified in construction.

In the second embodiment, a combination of the replying voice outputsection 113 and the post-processing section 114 functions as a voicegeneration section that is configured to generate voice of the acquiredreply, but also configured to control the pitches of the voice of theacquired reply in such a manner that the second segment of the voice hasa pitch associated with the analyzed pitch of the first segment.

<Application Examples and Modifications>

It should be appreciated that the present invention is not limited tothe above-described first and second embodiments and various otherapplication examples and modifications of the present invention are alsopossible as follows. Further, any selected ones of the plurality ofapplication examples and modifications may be combined as appropriate.

<Voice Input Section>

Whereas the embodiments of the invention have been described above inrelation to the case where the voice input section 102 inputs user'svoice (remark) via the microphone and converts the input voice (remark)into a voice signal, the present invention is not so limited, and thevoice input section 102 may be configured to receive a voice signal,processed by another processing section or supplied (or forwarded) fromanother device, via a recording medium, a communication network or thelike. Namely, the voice input section 102 may be configured in anydesired manner as long as it receives an input voice signal of aquestion or remark.

<Word Beginning and Word Ending in Reply or the Like>

Whereas the first and second embodiments have been described asconstructed to control the pitch of the word ending of a reply(response) in correspondence with the pitch of the word ending of aquestion, another portion of the reply (response) than the word ending,such as the word beginning, may sometimes become characteristic ordistinctive depending on the language, dialect, wording, way ofspeaking, etc. In such a case, when a person who gave a question hasreceived a reply (response) to the question judges an impression aboutthe reply (response) by unconsciously comparing the pitch of the wordending of the question and the pitch of the characteristic beginning ofthe reply (response). Thus, in this case, arrangements may be made forcontrolling the pitch of the word beginning of the reply (response) incorrespondence with the pitch of the word ending of the question. If theword beginning of the reply (response) is characteristic, sucharrangements can give a psychological impression to the user whoreceives the reply (response).

The same can be said for a reply or a remark, and it is conceivable thatan impression is sometimes judged based on the pitch of the beginning aswell as at the word ending. For a reply or remark, it is alsoconceivable that an impression is judged based on an average pitch, apitch of a portion where a word has been spoken with the greatestintensity, and/or the like. Therefore, it can be said that the firstsegment of a question and the second segment of a reply (response) arenot necessarily limited to the word ending and the beginning.

<Interval Relationship>

Whereas the above-described embodiments of the present invention areconstructed to control the voice synthesis such that the pitch of theword ending or the like of a reply (response) becomes five degrees downfrom the pitch of the word ending or the like of a question, the presentinvention may be constructed to control the pitch of the word ending orthe like of a reply (response) to assume a consonant interval of otherthan five degrees down from the pitch of the word ending or the like ofa question. For example, the consonant interval of other than fivedegrees down from than the word ending or the like of a question may bea perfect 8th or octave, perfect 5th, perfect 4th, major or minor 3rd,or major or minor sixth.

Further, there may be empirically recognized some interval relationshipswhich can give a good (or bad) impression although not in a consonantinterval relationship with the pitch of the word ending or the like of aquestion. Thus, the present invention may be constructed to control thepitch of a reply to assume any one of such interval relationships.However, in such a case too, the reply to the question tends to beunnatural if the pitch of the word ending or the like of the questionand the pitch of the word ending or the like of the reply (remark) aretoo remote from each other, and thus, it is desirable that the pitch ofthe reply is within an range of one octave up and one octave down fromthe pitch of the question.

<Pitch Shift of Reply>

In the aforementioned construction where the pitch of the word ending orthe like of a reply (response) defined by a voice sequence or voicewaveform data is controlled to assume a predetermined relationship withthe pitch of the word ending or the like of a question, morespecifically where the pitch of the word ending or the like of a replyis changed, for example, to be five degrees down from the pitch of theword ending or the like of the reply as in the above-describedembodiments, voice of the reply might be undesirably synthesized atunnaturally low pitch. The following describe application examples(Application Example 1 and Application Example 2) for avoiding such aninconvenience.

FIG. 10 is a flow chart showing primary portions of a process inApplication Example 1. The primary portions of the process inApplication Example 1 correspond to the operation performed in “pitchdetermination of reply” at step Sa17 shown in FIG. 4. Namely, inApplication example 1, the process shown in FIG. 10 are performed atstep Sa17 shown in FIG. 4, as will be described in detail later.

First, the voice synthesis section 112 obtains and provisionallydetermines a pitch of a reply (replying pitch) that is, for example,five degrees down from the pitch indicated by the pitch data suppliedfrom the pitch analysis section 106, at step Sb171. Then, the voicesynthesis section 112 determines, at step Sb172, whether or not theprovisionally-determined pitch is lower than a predetermined thresholdpitch (first threshold pitch). Note that the threshold pitch (firstthreshold pitch) is set, for example, at a pitch corresponding to alower-limit frequency to be used in synthesis of voice, at a pitch thatwould give an unnatural feel if it is lower than that pitch.

If the provisionally-determined pitch, i.e. the pitch five degrees downfrom the pitch of the word ending of the reply, is lower than thepredetermined threshold pitch (i.e., “Yes” determination at step Sb172),the voice synthesis section 112 shifts the provisionally-determinedpitch to a pitch one octave up from (higher than) theprovisionally-determined pitch, at step Sb173. If, on the other hand,the provisionally-determined pitch is equal to or high than thepredetermined threshold pitch (i.e., “No” determination at step Sb172),the operation of step Sb173 is skipped.

Then, the voice synthesis section 112 formally determines a target pitchto which the pitch of the reply is to be shifted, as a pitch of thereply, at step Sb174. Namely, if the provisionally-determined pitch islower than the threshold pitch, the voice synthesis section 112 formallydetermines, as the target pitch, the pitch to which theprovisionally-determined pitch has been shifted upward by one octave. Ifthe provisionally-determined pitch is equal to or higher than thethreshold pitch, the voice synthesis section 112 formally determines theprovisionally-determined pitch directly as the target pitch. Followingstep Sb174, the process revers to step Sa18 of FIG. 4. Thus, the voicesynthesis section 112 synthesizes voice of a voice sequence includingthe formally-determined pitch and outputs the thus-synthesized voice.

According to such Application example 1, the pitch to be changed isshifted one octave higher if it is lower than the threshold pitch, andthus, it is possible to avoid the inconvenience that voice of the replyis synthesized at unnaturally low pitch.

Whereas Application example 1 has been described above as shifting thepitch of the word ending or the like of reply one octave higher, thepresent invention is not so limited. For example, if theprovisionally-determined pitch is higher than another predeterminedthreshold pitch (second threshold pitch), the provisionally-determinedpitch may be shifted one octave lower. More specifically, if the pitchof the word ending or the like of a question given by the user is toohigh, the pitch five degrees down from the provisionally-determinedpitch too may sometimes be too high. In such a case, voice of a replywould be synthesized at unnaturally high pitch. If the pitch(provisionally-determined pitch) five degrees down from the pitchindicated by the pitch data is higher than the other predeterminedthreshold pitch (second threshold pitch), it just suffices to shift thepitch of the word ending or the like of the reply one octave down fromthe provisionally-determined pitch, in order to avoid the inconvenience.At least one of the above-described modification where the pitch of theword ending or the like of the reply is shifted one octave higher andthe above-described modification where the pitch of the word ending orthe like of the reply is shifted one octave lower may be carried out.

Further, in some case, the voice synthesis may output a reply with voiceof a virtual character of a predetermined sex and age (child or adult).If the pitch of the word ending of a reply is shifted uniformly fivedegrees down from the pitch of the word ending of a question as above inthe case where a female or child character is designated, voice of thereply would be synthesized at a low pitch unfit for the character, andthus, the pitch of the word ending of the reply may be shifted oneoctave higher.

FIG. 11 is a flow chart showing primary portions of a process in such anapplication example (Application Example 2). The primary portions of theprocess in Application example 2 correspond to the operation performedin “pitch determination of reply” at step Sa17 shown in FIG. 4. Theprocess in Application Example 2 shown in FIG. 11 is different from theprocess in Application Example 1 shown in FIG. 10 in that the voicesynthesis section 112 obtains and provisionally determines a pitch fivedegrees down from the pitch indicated by the pitch data supplied fromthe pitch analysis section 106 at step Sb171 and then determines at stepSc172 whether “female sex” or “child” is currently designated as anattribute defining the character in question.

If “female sex” or “child” is currently designated as the attribute(“Yes” determination at step Sc172), the voice synthesis section 112shifts the provisionally-determined pitch one octave higher at stepSb173. If, on the other hand, “female sex” or “child” is not currentlydesignated as the attribute, and if “male sex” or “adult” is currentlydesignated as the attribute (“No” determination at step Sc172), theaforementioned operation of step Sb173 is skipped. A subsequentoperation is the same as in Application Example 1.

According to such Application Example 2, the provisionally-determinedpitch is shifted one octave higher if settings have been made togenerate a reply with female or child voice, and thus, it is possible toavoid the inconvenience that the voice of the reply is synthesized atunnaturally low pitch.

Whereas Application example 2 has been described above as constructed toshift the provisionally-determined pitch one octave higher if “femalesex” or “child” is currently designated as the attribute, theprovisionally-determined pitch may be shifted one octave lower, forexample, if “adult male” is currently designated as the attribute, inorder to avoid the inconvenience that voice of the reply would besynthesized at pitch unfit for the character.

<Dissonant Interval>

Whereas the above-described embodiments are constructed to control thevoice synthesis in such a manner that the pitch of the word ending orthe like of a reply (response) to a question assumes a consonantinterval relationship with the pitch of the word ending or the like of aquestion, the voice synthesis may be controlled in such a manner thatthe pitch of the word ending or the like of a reply (response) assumes adissonant interval relationship with the pitch of the word ending or thelike of a question. If voice of the reply is synthesized with a pitchthat is in dissonant interval relationship with the pitch of the wordending or the like of the question, there may occur an undesirablelikelihood that an unnatural feeling, bad impression, nasty feeling,etc. are given to the user having given the question so that a smoothdialogue cannot be established. Conversely, however, there is also anopinion that such feelings are good for stress relieving. Thus, in thepresent invention, an operation mode (first mode) in which a reply ofgood impression etc. is desired and another operation mode (second mode)in which a reply of bad impression etc. may be prepared so that thevoice synthesis is controlled in accordance with any one of the firstand second modes.

Further, FIG. 12 is a flow chart showing primary portions of a processin such an application example (Application Example 3). The primaryportions of the process in Application example 3 correspond to theoperation performed in “pitch determination of reply” at step Sa17 shownin FIG. 4. The process in Application Example 3 shown in FIG. 12 isdifferent from the process in Application Example 1 shown in FIG. 10 asfollows. Namely, the voice synthesis section 112 in Application Example3 determines at step Sd172 whether the first mode is currently set asthe operation mode.

If the first mode is currently set as the operation mode (“Yes”determination at step Sd172), the voice synthesis section 112 sets theword ending of, for example, the reply at a pitch that is in a consonantinterval relationship with the pitch of, for example, the word ending ofthe question, at step Sd173A. If, on the other hand, the second mode iscurrently set as the operation mode (“No” determination at step Sd172),the voice synthesis section 112 sets the word ending of the reply at apitch that is in a dissonant interval relationship with the pitch of theword ending of the question, at step Sd173B. A subsequent operation isthe same as in Application Example 1 and in Application Example 2.

Namely, according to Application Example 3, voice of the reply(response) is synthesized at a pitch that is in a consonant intervalrelationship with the word ending of the question if the first mode iscurrently set, but voice of the reply (response) is synthesized at apitch that is in a dissonant interval relationship with the word endingof the question if the second mode is currently set. Thus, according toApplication Example 3, the user can appropriately use any one of the twomodes depending on the case. Note that setting of any one of the firstand second modes may be performed in any desired manner, e.g. through aselection operation by the user or through automatic selection based on,for example, an instruction generated within the apparatus duringexecution of the application program.

Whereas Application Example 1, Application Example 2 and ApplicationExample 3 have been described above in relation to the case where isused a voice sequence similar to that used in the first embodiment, theymay of course use a voice sequence similar to that used in the secondembodiment.

<Voice of Reply>

Whereas the above-described embodiments are constructed to make voice ofa reply through synthesis of human voice (i.e., generate a reply insynthesized human voice), voice of the reply may be made throughsynthesis of animal's voice (i.e., generated in synthesized animalvoice). Namely, the term “voice” is used herein to refer to a conceptembracing animal's voice as well as human voice. Thus, the followingdescribe Application Example 4 where voice of a reply is made throughsynthesis of animal's voice (i.e., generated in synthesized animalvoice).

FIG. 13 is a diagram outlining a process performed in ApplicationExample 4. In the case where voice of a reply is made through synthesisof animal's voice, the process is configured to only shift the pitch ofthe word ending of animal's voice to a predetermined pitch in responseto the pitch of the word ending of the question. Therefore, it is notnecessary to perform operations for analyzing the meaning of thequestion, acquiring information corresponding to the analyzed meaning,creating a reply corresponding to the information, etc.

Once the user W utters and inputs a question “ii tenki dane” (romanizedJapanese meaning “It is a fine weather, isn't it?”) into the voicesynthesis apparatus 10, the voice synthesis apparatus 10 analyzes apitch of “ne” (romanized Japanese) constituting to the word ending ofthe question. If the pitch of “ne” is “G”, the voice synthesis apparatus10 post-processes voice waveform data of dog's voice “wan” (romanizedJapanese) and changes the pitch of “n”, constituting the word ending of“wan”, into “C” that is a pitch five degrees down from, i.e. in anexample of a consonant interval relationship with, the pitch of the wordending of the question, so that the voice synthesis apparatus 10 outputsthe thus-changed pitch “C”.

In the case where voice of the reply is made through synthesis ofanimal's voice, information desired by the user cannot be obtained fromthe reply. Namely, when the user has asked a question “asu no tenki wa?”(romanized Japanese meaning “How will the weather be tomorrow?”), theuser cannot get the tomorrow's weather information. However, if, inresponse to some user's question, animal's voice is synthesized in sucha manner that the pitch of the word ending of the animal's voice assumesan interval relationship of, for example, five degrees down from thepitch of the word ending of the question, the animal's voice can givethe user a comfortable, reassuring good impression; in this respect,this application example is the same as the case where the reply isgenerated in synthesized human voice. Thus, even where the reply isgenerated in animal's voice, it can be expected to give the user a kindof healing effect as if the user were actually communicating with avirtual animal uttering the voice.

As an example, a display section may be provided on the voice synthesisapparatus 10 so that a virtual animal can be displayed on the displaysection as shown in FIG. 13(b). Also, the virtual animal may bedisplayed on the display section in animated images wagging the tail,inclining the head, etc. Such arrangements can further enhance thehealing effect.

If the animal whose voice is to be synthesized is a dog, thisapplication example may be configured to permit selection from amongvarious dog types, such as chihuahua, pomeranian and golden retriever.The voice synthesis apparatus 10 constructed to create a reply withsynthesized animal's voice as above may be applied to other thanterminal apparatus, such as robot pets, stuffed toys, etc. mockingdesired animals.

<Others>

In the above-described embodiments, the linguistic analysis section 108,the linguistic database 202 and the reply database 204, constructed toacquire a reply (response) to a question (remark), are provided in thevoice synthesis apparatus 10. However, in view of the inconveniencesthat a processing load tends to become heavy and storage capacity islimited in terminal apparatus, etc., the above-mentioned linguisticanalysis section 108, the linguistic database 202 and the reply database204 may be provided in the external server. Namely, it is only necessarythat the reply creation section 110 (replying voice output section 113)in the voice synthesis apparatus 10 be configured to acquire a reply toa question in some way and output a voice sequence (voice waveform data)of the reply, and it does not matter at all whether the reply is createdin the voice synthesis apparatus 10 or in a structure other than thevoice synthesis apparatus 10, such as the external server. In anapplication where a reply (response) to a question (remark) can becreated in the voice synthesis apparatus 10 without accessing theexternal server or the like, the information acquisition section 126 canbe dispensed with.

<Third Embodiment>

Next, a third embodiment of the present invention will be described withreference to FIG. 14. The third embodiment of the present invention ischaracterized in that the voice synthesis is controlled in accordancewith non-linguistic (non-verbal) information included in an input voicesignal of a question (remark). FIG. 14 is a block diagram showing aconstruction of the third embodiment of the voice synthesis apparatus 10of the present invention. Blocks in FIG. 14 that implement substantiallythe same functions as those in FIG. 1 are depicted by the same referencecharacters as in FIG. 1 and will not be described to avoid unnecessaryduplication. The third embodiment of FIG. 14 include a non-linguisticanalysis section 107 and a voice control section 109 in addition to theconstruction shown in FIG. 1.

The non-linguistic analysis section 107 analyzes a voice signal detectedas an utterance section by the voice-utterance-section detection section104 and outputs non-linguistic information other than pitch (other thanpitch information). Although speed (speaking speed), quality and volumeof the voice, facial expression, gesture and clothes of the user havinggiven the question, etc. are assumable as examples of the non-linguisticinformation, let it be assumed that the speed and volume of the voiceare analyzed as the non-linguistic information in the instantembodiment. Namely, the non-linguistic analysis section 107 in theinstant embodiment analyzes the speed and volume of the question(remark) and outputs the analyzed speed and volume as the non-linguisticinformation other than pitch information. Note that the volume of theinput voice signal analyzed by the non-linguistic analysis section 107is supplied to the pitch analysis section 106, as indicated by brokenline, so that the volume can be used as volume information foridentifying a pitch of the first segment.

The voice control section 109 controls the voice synthesis section 112in accordance with the pitch data output from the pitch analysis section106 and the non-linguistic information (speed and volume) output fromthe non-linguistic analysis section 107. The following describe, withreference to FIG. 15, how the voice synthesis section 112 is controlledby the voice control section 109.

FIG. 15 is a flow chart of a process performed in the third embodimentof the voice synthesis apparatus 10. FIG. 15 is shown as a modificationof FIG. 4, where steps performing substantially the same operations asin FIG. 4 are depicted by the same reference characters and will not bedescribed here to avoid unnecessary duplication.

Once an utterance section is detected at step Sa12, the non-linguisticanalysis section 107 analyzes the speed (speaking speed) of the questionfrom the voice signal of the detected utterance section and outputsspeed data indicative of the speed, at step Sa19. In parallel with thespeed analysis at step Sa19, the non-linguistic analysis section 107performs the following volume analysis at step Sa20. Namely, thenon-linguistic analysis section 107 obtains, for example, an averagevolume of the voice signal of the question (remark) in the detectedutterance section to thereby output volume data indicative of theaverage volume, and apart from such volume data outputting, thenon-linguistic analysis section 107 obtains a volume waveform of thevoice signal. An example of the volume waveform obtained here is similarto the volume waveform shown in FIG. 5(a).

After changing the pitch of the word ending (second segment) of thereplying voice at step Sa17, the voice control section 109 proceeds tostep Sa21. At step Sa21, the voice control section 109 determines thatthe voice synthesis section 112 should synthesize voice of the entirereply (response) with a volume corresponding to the volume dataindicative of the average volume of the reply (response). Then, at stepSa22, the voice control section 109 determines that the voice synthesissection 112 should synthesize voice of the entire reply (response) at aspeed corresponding to the speed data. Further, at next step Sa18, thevoice synthesis section 112 synthesizes and outputs the voice of thevoice sequence, whose change has been determined by the voice controlsection 109, with the determined volume and at the determined speed.

<Fourth Embodiment>

Next, a fourth embodiment of the present invention will be described asa modification of the replying voice generation method employed in thethird embodiment. FIG. 16 is a block diagram showing a construction ofthe fourth embodiment of the voice synthesis apparatus 10 of the presentinvention. Similarly to the voice synthesis apparatus 10 shown in FIG.8, the voice synthesis apparatus 10 shown in FIG. 16 is constructed insuch a manner that the replying voice output section 113 acquires areply (response) to a question (remark) and generates voice waveformdata of the entire reply (response), and that the post-processingsection 114 a performs control for changing the pitch of the word ending(second segment) of the replying voice. Blocks in FIG. 18 that implementsubstantially the same functions as those in FIG. 8 are depicted by thesame reference characters as in FIG. 8 and will not be described toavoid unnecessary duplication. The fourth embodiment of FIG. 18 includesthe non-linguistic analysis section 107 in addition to the constructionshown in FIG. 8, and the post-processing section 114 a in the fourthembodiment is slightly different from the post-processing section 114shown in FIG. 8. The non-linguistic analysis section 107 in FIG. 18 isconstructed similarly to the non-linguistic analysis section 107 in FIG.14.

In addition to performing control for changing pitches of entire voicewaveform data of replying voice in such a manner that the pitch of theword ending of the reply (responsive output) assumes a predeterminedinterval relationship (such as a consonant interval relationship) withthe pitch of the word ending of the question (uttered input) in asimilar manner to the post-processing section 114 of FIG. 8, thepost-processing section 114 a in the fourth embodiment performs controlfor reproducing the entire replying voice waveform data, output from thereplying voice output section 113, with an intensity corresponding tothe volume of the analyzed non-linguistic information and/or at a speedcorresponding to the speed of the non-linguistic information. Namely, inthe fourth embodiment, the post-processing section 114 a controls thevolume and reproduction speed of the entire replying voice in additionto the pitch control of the replying voice.

<Fifth Embodiment>

In a dialogue between persons, a person having quickly uttered aquestion (remark) generally has an impatient, hasty or other similarcharacter or psychological state, and thus, it is considered that personwants to promptly have a reply (response) to the question (remark). Onthe other hand, a person having slowly made a question (remark)generally is, for example, in a careful and calm state, and thus, it isconsidered that person is ready to wait for a reply (response) to thequestion patiently.

Thus, the fifth embodiment is constructed to control voice synthesisstart timing (i.e., time interval or pause from the end of the questionto a time when voice synthesis of a reply is started) in accordance withnon-linguistic information of the question (remark), i.e. speed of thequestion (remark) in this case.

The fifth embodiment of the voice synthesis apparatus 10 may besubstantially the same as the third embodiment shown in FIG. 14 as longas it is constructed to use a voice sequence. However, the voice controlsection 109 in the fifth embodiment controls the voice synthesis section112 to delay the voice synthesis start timing, for example, as the speedof the question indicated by the speed data of the non-linguisticinformation decreases.

FIG. 17 is a diagram explanatory of the voice synthesis performed in thefifth embodiment. If the user W quickly inputs a question “ashita notenki wa?” (romanized Japanese meaning “How will the weather betomorrow?”) into the voice synthesis apparatus 10, an example reply“hare desu” (romanized Japanese meaning “It is fine tomorrow.”) will beoutput in voice at relatively early timing, and the overall speed of thereply will be quick, as shown in FIG. 17(a). On the other hand, if theuser W slowly inputs the same question “ashita no tenki wa?” into thevoice synthesis apparatus 10, the reply “hare desu” will be output invoice at relatively late timing, and the overall speed of the reply willbe slow, as shown in FIG. 17(b).

Note that, in the figure, a time interval or pause from the time whenthe question was uttered to the time when the voice synthesis of thereply was started is represented by a time period Ta or Tb (Ta<Tb) fromthe word ending of the question to the word beginning of the reply.Needless to say, the pause may be defined in any other suitable mannerthan the aforementioned. In the figure, smaller intervals betweencharacters (letters) in the question and in the reply indicate that thequestion and the reply were uttered quickly.

With the fifth embodiment constructed in the aforementioned manner, areply can be given to the user, who wants to get a reply to thequestion, with a natural feel and in accordance with a character andpsychological condition of the user as if a dialogue were beingconducted between persons.

If voice waveform data is used in place of the voice sequence, the fifthembodiment is constructed in substantially the same manner as the fourthembodiment shown in FIG. 16. In such a construction, the post-processingsection 114 a delays the start timing of voice output as the speed ofthe non-linguistic information decreases. Further, whereas the fifthembodiment is constructed to control the start timing of voice output inaccordance with the speed of the question, the speed in accordance withwhich the start timing of voice output is controlled may be replacedwith volume or pitch, and other information than the speed, volume andpitch may be combined as appropriate.

<Sixth Embodiment>

Application examples and/or modifications similar to the aforementionedvarious examples and/or modifications of the first and secondembodiments may be applied to the third, fourth and fifth embodiments.For example, FIG. 18 is a flow chart showing, as a sixth embodiment ofthe present invention, an example of a reply pitch determination routinein a case where operation modes similar to the operation modes shown inFIG. 12 are applied. FIG. 18 is similar to FIG. 12 except in that stepsSd174A and Sd174B are added in FIG. 18.

The example shown in FIG. 18 is constructed to perform control takinginto account a “pause” of a reply to a question. Normally, in a dialoguebetween persons, if one of the persons attempts to reply to a questionin such a manner as to intentionally give a bad impression, the pause ofthe reply to the question is extremely shortened or extremely lengthenedas compared to than in other cases. In a scene like a quarrel, forexample, one person tends to argue back to another person's remarkpromptly (substantially with no pause) or intentionally with a longpause. In the illustrated example shown in FIG. 18, the control isperformed taking such a “pause” into account.

If the first mode is currently set as the operation mode in the exampleof FIG. 18, the voice control section 109 proceeds to step Sd174A,following step Sd173A, where it determines, as an instruction to begiven to the voice synthesis section 112, that the voice synthesisshould be started within a predetermined time range following the wordending of the question (remark). Because, the “predetermined time range”is in the range of 0.5 to 2.0 sec, and the aforementioned pause isconsidered to be an appropriate pause as long as it is within thisrange.

If, on the other hand, the second mode is currently set as the operationmode (i.e., “No” determination at step Sd172), the voice control section109 determines, at step Sd173B, that the pitch of the word ending of thereply should assume a dissonant interval relationship with the pitch ofthe word ending of the question. Then, at step Sd174B, the voice controlsection 109 determines, as an instruction to be given to the voicesynthesis section 112, that the voice synthesis should be startedoutside the predetermined time range following the word ending of thequestion.

After step Sd174A or Sd174B, the process reverts to step Sa21 of FIG.15, so that the voice control section 109 determines an overall volumeof the reply at step Sa22. After that, at step Sa18, the voice synthesissection 112 synthesizes voice of a voice sequence, whose change has beendetermined by the voice control section 109, at determining timing andspeed and with a determined volume, and then outputs thethus-synthesized voice.

Namely, according to the sixth embodiment shown in FIG. 18, the “pause”is controlled to be within the predetermined time range when theoperation mode is the first mode, while the “pause” is controlled to beoutside the predetermined time range when the operation mode is thesecond mode. Thus, the user can appropriately use any desired one of thetwo modes, so that usability of the apparatus can be enhanced. Theapplication example shown in FIG. 18 is applicable to not only the thirdembodiment constructed to the replying voice synthesis per syllablebased on a voice sequence, but also to the fourth embodiment constructedto generate replying voice waveform data of the entire replying voice.

<Seventh Embodiment>

Whereas each of the third to sixth embodiments has been described asusing, as the non-linguistic information, information related to aquestion (remark) itself uttered by the user, such as pitch, volume andspeed, other information, such as facial expression, gesture and closes,may be used as the non-linguistic information. Thus, the followingdescribe a seventh embodiment of the present invention which usesnon-voice information as the non-linguistic information.

FIG. 19 is a block diagram showing a construction of the seventhembodiment of the voice synthesis apparatus 10 of the present invention,which is characterized by including an imaging section 130 for imagingareas around the voice synthesis apparatus 10. In the instantembodiment, the non-linguistic analysis section 107 analyzes a facialexpression (laugh, embarrassment, anger, or the like) of the user from astill image taken by the imaging section 130 and reflects a result ofthe analysis in voice synthesis processing as follows.

When the user has uttered a question while laughing, for example, a highpitch tends to be detected in the pitch analysis of the question by thepitch analysis section 106. Thus, the non-linguistic analysis section107 causes the pitch analysis section 106 to adjust the detected pitchto a lower pitch. When the user has uttered a question angrily, on theother hand, a low pitch tends to be detected in the pitch analysis ofthe question by the pitch analysis section 106. Thus, the non-linguisticanalysis section 107 causes the pitch analysis section 106 to adjust thedetected pitch to a lower pitch. By thus adjusting a result of the pitchanalysis by the pitch analysis section 106 in accordance with the facialexpression of the user, the instant embodiment can achieve an enhancedaccuracy of the pitch detection and analysis.

Further, the voice synthesis apparatus 10 is constructed in such amanner that, if the user has an embarrassed facial expression after thevoice synthesis apparatus 10 has synthesized and output voice of thereply (response), the pitch of the word ending of the reply is changedto assume an interval relationship of five degrees down from the pitchof the word ending of the question. However, it is conceivable that suchan interval relationship is not maintained correctly. Thus, thenon-linguistic analysis section 107 causes the voice control section 109to change the five-degree-down interval relationship of the reply withthe question to another interval relationship, such as four degrees downfrom the pitch of the word ending of the question. Alternatively, thenon-linguistic analysis section 107 causes the voice control section 109to change a pitch analysis algorithm (e.g., which local maximum of apitch waveform should be set as the word ending, pitch of which portionof the word ending should be determined, etc.) in the pitch analysissection 106, because it is also conceivable that accuracy of the pitchanalysis, by the pitch analysis section 106, has been lowered. Bycontrolling the pitch analysis and voice synthesis in accordance withthe user's facial expression as above, the instant embodiment can directthe reply, whose voice is to be synthesized, in such a direction as togive no uncomfortable feeling.

Whereas the instant embodiment has been described above in relation tothe case where the pitch analysis and voice synthesis are controlled inaccordance with the user's facial expression, it may be constructed toanalyze user's gesture, clothes, etc. from an image of the user taken bythe imaging section 130 so that the pitch analysis and voice synthesisis controlled in accordance with such user's gesture, clothes, etc.Further, there may be provided a humidity sensor and/or the like, inplace of or in addition to the imaging section 130, so that informationof ambient environment acquired via the humidity sensor and/or the likeis used to control the voice synthesis. For example, in hot and humidenvironment, voice of a reply that is expected to ease frustration maybe synthesized.

<Fluctuation of Applied Rule, Etc.>

Each of the third to sixth embodiments is constructed to determine avolume, speed and pause of a reply on the basis of a volume and speed ofa question (remark) and in accordance with the above-described rule.However, if the rule is fixed, the reply tends to give the user animpression that the reply is monotonous. Thus, arrangements may be madefor giving fluctuation to the rule to thereby modify the rule, forexample, within such a range that the created reply does not give anunnatural feel, or a plurality of rules within such a range may beprepared in advance so that any one of the rules can be selected to beapplied to the voice synthesis. Such arrangements can effectively avoidgiving a monotonous reply to the user.

Each of the third to seventh embodiments of the present invention may besummarized as follows. Namely, each of the third to seventh embodimentsincludes: the non-linguistic analysis section 107 for analyzingnon-linguistic information other than pitch information related to aquestion (i.e., remark); and the control section (voice control section109) for controlling generation, by the voice generation section (i.e.,the voice synthesis section 112 or the combination of the replying voiceoutput section 113 and the post-processing section 114 a), of voice of areply in accordance with the analyzed non-linguistic information. Notethat the various application examples and/or the modifications relatedto the first and second embodiments are also applicable to the third toseventh embodiments of the present invention.

<Eighth Embodiment>

The following describe, with reference to FIG. 20, an eighth embodimentof the voice synthesis apparatus of the present invention, which ischaracterized by controlling generation of replying voice in accordancewith linguistic information included in a remark (question) and a reply(response). FIG. 20 is a block diagram showing a construction of theeighth embodiment of the voice synthesis apparatus of the presentinvention. Blocks in FIG. 20 that implement substantially the samefunctions as those in FIG. 1 are depicted by the same referencecharacters as in FIG. 1 and will not be described to avoid unnecessaryduplication. The eighth embodiment of FIG. 20 includes a voice controlsection 109A in addition to the construction shown in FIG. 1, and thelinguistic analysis section 108A in the eighth embodiment is differentin construction from the linguistic analysis section 108 shown in FIG.1.

The linguistic analysis section 108A in the eighth embodiment not onlyanalyzes a linguistic meaning contained in a voice signal of a remark(question), but also analyzes a meaning of a reply (response) created(acquired) by the reply creation section 110. The linguistic analysissection 108A supplies an analyzed result of the meaning of the remark(question) to the reply creation section 110, and when the reply(response) has been received from the reply creation section 110, thelinguistic analysis section 108A analyzes the meaning of the receivedreply (response) and supplies an analyzed result of the meaning of thereply (response) to the voice control section 109A.

In the eighth embodiment, the reply creation section 110 may create(acquire) the following types of reply:

(1) reply indicative of an affirmative meaning;

(2) reply indicative of a negative meaning;

(3) specific reply to a question; and

(4) sympathetic reply (including back-channel feedback) uttered prior tothe specific reply. Examples of the type (1) reply above include “Yes”or “hai” (romanized Japanese), and examples of the type (2) reply aboveinclude “No” or “iie” (romanized Japanese). Examples of the type (3)reply above include a reply specifically answering a question like “asuno tenki wa?” (romanized Japanese). Further, examples of the type (4)reply above include “to” (mmanized Japanese meaning “Let me see.”) and“sou desune” (romanized Japanese meaning “Well, . . . ”). The replyingvoice sequence created by the reply creation section 110 is supplied tothe voice control section 109A and the voice synthesis section 112.

The voice control section 109A determines, in accordance with the pitchdata supplied from the pitch analysis section 106 and the meaning of thereply supplied from the linguistic analysis section 108A, content ofcontrol to be performed on the replying voice sequence. The followingdescribe, with reference to FIG. 21, the content of the control by thevoice control section 109A.

FIG. 21 is a flow chart of a process performed in the eighth embodimentof the voice synthesis apparatus 10. FIG. 21 is shown as a modificationof FIG. 4, and steps that perform substantially the same operations asthose in FIG. 4 are depicted by the same reference numerals as in FIG. 4and will not be described to avoid unnecessary duplication.

At step Sa14 of FIG. 21, the linguistic analysis section 108A analyzes ameaning of words (question or remark) defined by a voice signal andsupplies data indicative of the meaning to the reply creation section110. Then, at step Sa15 a, the reply creation section 110 creates areply corresponding to the analyzed words (question) by use of the replydatabase 124 and, as necessary, the information acquisition section 126,and supplies the created reply to the linguistic analysis section 108A.Note that the reply created (read out from the reply database 124) is areply of any one of the types (1), (2) and (4) to the question. Althoughnot shown in the flow chart, a specific reply, i.e. a reply of the type(3), is created after the type (4) reply. At step Sa15 b, the replycreation section 110 outputs a voice sequence of the created or acquiredreply.

FIG. 22(a) shows an example voice sequence of an affirmative reply “hai”(romanized Japanese meaning “yes”) of the type (1). In the illustratedexample of FIG. 22(a), a note is allocated to each sound (i.e., eachsyllable) of the reply “hai” so that a pitch and generation timing ofeach word (syllable or phoneme) is indicated. Whereas one note isallocated to each sound (i.e., each syllable or phoneme) in theillustrated example for simplicity of explanation, a plurality of notesmay be allocated to a sound by use of a note-connecting symbol, such asa slur or glissando, a plurality of sounds of different pitches may beinterconnected transiently, etc.

FIG. 23(a) shows an example voice sequence of a negative reply “iie”(romanized Japanese) of the type (2), and FIG. 24(a) shows an examplevoice sequence of a reply “êto” (romanized Japanese meaning “Let mesee”) of the type (4).

The linguistic analysis section 108A analyzes the meaning of the replysupplied from the reply creation section 110, at step Sa23. In theinstant embodiment, the linguistic analysis section 108A identifieswhich one of the types (1), (2) and (4) the reply is of and thensupplies a result of the type identification to the voice controlsection 109A.

The voice control section 109A determines, at step Sa24, pitches of theentire replying voice sequence, output from the reply creation section110, such that the pitch of the second segment of the replying voicesequence output from the reply creation section 110 assumes thefollowing interval relationship with a pitch of the first segment (e,g., word ending) of pitch data supplied form the pitch analysis section106.

More specifically, for the affirmative reply of the type (1), the voicecontrol section 109A decides to shift the pitches of the entire replyingvoice sequence so that the pitch of the second segment (word ending) ofthe reply is changed to five degrees down from the pitch of the firstsegment (e, g., word ending) of the pitch data of the remark (question).

For the negative reply of the type (2), the voice control section 109Adecides to shift the pitches of the entire replying voice sequence sothat the pitch of the second segment (word ending) of the reply ischanged to six degrees down from the pitch of the first segment (e, g.,word ending) of the pitch data of the remark (question). Namely, thepitch of the second segment of the affirmative reply of the type (1) areset to be higher than the pitch of the second segment of the negativereply of the type (2).

For the reply of the type (4), the voice control section 109A decides toshift the pitches of the entire replying voice sequence in such a mannerthat the pitch of the second segment (word ending) of the reply ischanged to, for example, five degrees down from the pitch of the firstsegment (e, g., word ending) indicated by the pitch data of the remark(question).

More specifically, consider a case where, of a question “asu wa hare?”(romanized Japanese meaning “ ” will it be fine tomorrow?), the pitch of“re” at the word ending depicted at reference character A in FIG. 22(b)is indicated as “pitch E” by the pitch data. In such a case, for thevoice sequence of the affirmative reply “hai” (romanized Japanese) ofthe type (1), the voice control section 109A decides to shift thepitches defined in the entire replying voice sequence such that thepitch of “i” at the word ending of the reply depicted at referencecharacter B in FIG. 22(b) becomes “pitch A” that is five degrees downfrom the pitch “E” of the word ending of the question.

Further, for the negative reply “iie” (romanized Japanese) of the type(2), the voice control section 109A decides to shift the pitches definedby the entire replying voice sequence such that the pitch of “e” at theword ending of the reply depicted at reference character C in FIG. 23(b)becomes “pitch G” that is six degrees down from the pitch “E” of theword ending of the question.

Also consider a case where, of a question “asu no tenki wa” (romanizedJapanese meaning “How will the weather be tomorrow?”), the pitch of “wa”at the word ending depicted at reference character A in FIG. 24(b) isindicated as “pitch E” by the pitch data. In such a case, for the voicesequence “êto” (romanized Japanese) of the type (4), the voice controlsection 109A determines the pitches defined in the voice sequence suchthat the pitch of “to” at the word ending depicted at referencecharacter D in FIG. 24(b) becomes “pitch A” that is five degrees downfrom the pitch “E” of the word ending of the question.

Referring now back to FIG. 21, the voice control section 109A determinesoutput timing, i.e. “pause”, of the replying voice sequence, at stepSa25. More specifically, the voice control section 109A sets a “pause”from the word ending of the question to outputting of the reply in arange of 0.5-2.0 sec for the affirmative reply of the type (1), or inthe neighborhood of 3.0 sec, longer than the range for the type (1), forthe negative reply of the type (2). Thus, the replying voice sequencefor the affirmative reply of the type (1) will be output at earliertiming than the replying voice sequence for the negative reply of thetype (2). Note that, for the reply of the type (4), the voice controlsection 109A sets a “pause” in the same range of 0.5-2.0 sec as for thereply of the type (1).

At step Sa18, the voice control section 109A controls the voice controlsection 112 to shift the voice sequence, supplied from the replycreation section 110, to the determined pitches and output thepitch-shifted voice sequence at the determined timing. In accordancewith such control, the voice control section 112 changes the pitches ofthe voice sequence and synthesizes and outputs voices of the reply atthe changed pitches.

For the replying voice output timing, the voice control section 109A maycontrol the voice control section 112 to start the output of the voicesequence at a time point when a time measured by a realtime clock (notshown) starting at the word ending of the question, e.g. time point ofthe local maximum P1 (FIG. 5), has elapsed a preset time.

Although not particularly shown, the voice control section 112 isconstructed so that, if it has output the replying voice of the type(4), it then outputs specific replying voice of the type (3). In theaforementioned manner, the execution of the application program isterminated, and the process returns to the menu screen.

FIG. 25 is a diagram explanatory of output of replying voice of the type(1) or (2) in response to a question uttered by the user. Morespecifically, FIG. 25 shows a case where the voice synthesis apparatus10 that is a terminal apparatus outputs “hai” or “iie” to a question“asu wa hare” (romanized Japanese meaning “will it be fine tomorrow”)uttered by the user W.

In the illustrated example of FIG. 25, voice synthesis is performed insuch a manner that the pitch of the word ending of the reply “hai” or“iie” assumes a consonant interval relationship of five or six degreesdown from the pitch of the word ending of the question. Thus, the replycan give an impression as if a dialogue with a person were taking place,without giving an unnatural feel to the user.

What kind of relationships the pitch of the word ending of the reply“hai” of the type (1) and the pitch of the word ending of the reply“iie” of the type (2) assume with respect to the pitch of the wordending of the question in the illustrated example of FIG. 25 has alreadybeen described above in relation to FIGS. 22 and 23. The pitch of theword ending of the negative reply “iie” tends to be lower than the pitchof the word ending of the reply affirmative “hai”. Thus, when replyingwith the negative meaning in the instant embodiment, the negative replyis output in low voice with such consideration as to not put the otherperson or other party in a bad mood. In this sense too, the instantembodiment can give an impression as if the user were actually dialogingwith a person. Further, when outputting the negative reply of the type(2), the voice control section 109A may make the volume of the replymodest (i.e., lower the volume of the reply) as compared to the volumeof the affirmative reply of the type (1).

Further, in the illustrated example of the figure, a time point when thequestion is uttered, e.g. a time point of “re” at the word ending, isindicated by (a), a time point when the word beginning of the reply“hai” is uttered is indicated by “b”, and a time point when the wordbeginning of the reply “iie” is uttered is indicated by “c”. A timeperiod T1 from the utterance of the question to the time point when thereply “hai” is output is shorter than a time period T2 from theutterance of the question to the time point when the reply “iie” isoutput; that is, T1<T2. In other words, in the instant embodiment of thevoice synthesis apparatus 10, the reply “iie” is output slightly laterthan the reply “hai”. Thus, according to the present invention, replies,such as “hai” and “iie”, can be output in synthesized voice, with pausessimilar to those taken in an actual dialogue with a person.

FIG. 26 is a diagram explanatory of output of replying voice of thetypes (3) or (4) to the question uttered by the user. More specifically,FIG. 26 shows a case where the voice synthesis apparatus 10 outputs aspecific reply a question “asu no tenki wa” (romanized Japanese meaning“How will the weather be tomorrow?”) uttered by the user. In theillustrated example of FIG. 26, a reply “êto” of the type (4) is outputin response to the question before a specific reply of the type (3) isoutput. Because it is necessary to access any of various databases andexternal servers for creating the specific reply, it may sometimes takea relatively long time to create the reply. If a considerably longsilent state continues in the voice synthesis apparatus 10 until thespecific reply is created, a feeling of anxiety would be given to theuser. However, in the instant embodiment, where the reply of the type(4) is tentatively output, no such feeling of anxiety is given to theuser. Further, in actual dialogues between persons, uttering such a type(4) reply before replying with specific content is a commonly-doneactivity. Because the instant embodiment is constructed to synthesizevoice of a reply by imitating such a commonly-done activity, it can givethe user an impression as if the user were actually dialoging with aperson.

In the illustrated example of the figure, a time point when the questionis uttered, e.g. a time point of “wa” at the word ending of the reply,is indicated by (d), a time point when the word beginning of the reply“êto” is uttered is indicated by “e”, and a time point when the wordbeginning of the reply “hare desu” is uttered is indicated by “f”. It ispreferable that a time period T3 from the utterance of the question tillthe time point when the reply “êto” be substantially equal to the timeperiod T1 of the reply of the type (1). If it takes a long time tocreate a specific reply like “hare desu”, the same reply “êto” oranother reply may be repeated, as the type (4) reply, to provide a pauseof an increased time length.

<Modification Using Voice Waveform Data>

Whereas the eighth embodiment of the present invention has beendescribed as constructed to output, as a reply to a question, a voicesequence where a pitch is allocated per sound (per syllable), the eightembodiment may be modified in a similar manner to the above-describedsecond embodiment. Namely, a combination of the reply creation section110 and the voice synthesis section 112 of FIG. 20 (i.e., the voicegeneration section using the voice synthesis technique) may be replacedwith the combination of the replying voice output section 113 and thepost-processing section 114 (i.e., the voice generation section usingwaveform data), and voice waveform data, for example, in the WAV formatmay be output from the replying voice output section 113.

In such a case, the post-processing section 114 can be constructed, forexample, to output (reproduce) the voice waveform data after performingpitch conversion, such as a filtering process, such that the pitch ofthe second segment (e.g., word ending) of the reply assumes apredetermined interval relationship with the pitch of the first segment(e.g., word ending) in the pitch data of the remark (question). Further,the pitch conversion may be performed using the so-called key controltechnique that shifts pitches without changing a speech rate (speakingspeed) as well known in the field of karaoke equipment.

Note that the various application examples and/or the modificationsrelated to the first and second embodiments are also applicable to theeighth embodiment of the present invention.

In short, the eighth embodiment of the present invention ischaracterized by including: a linguistic analysis section (linguisticanalysis section 108A) that analyzes linguistic information contained ina question (remark) and a reply; and a control section (voice controlsection 109A) that controls generation, by the voice generation section(i.e., the voice synthesis section 112 or the combination of theresponsive output section 113 and the post-processing section 114), ofvoice of the reply.

<Ninth Embodiment>

The following describe, with reference to FIG. 27, a ninth embodiment ofthe voice synthesis apparatus of the present invention, which ischaracterized by controlling pitch variation in a reply (response) inaccordance with pitch variation over time in a remark (question). FIG.27 is a functional block diagram of the ninth embodiment of the voicesynthesis apparatus 10 of the present invention. Blocks in FIG. 27 thatimplement substantially the same functions as those in FIG. 1 aredepicted by the same reference characters as in FIG. 1 and will not bedescribed to avoid unnecessary duplication. The embodiment of FIG. 27includes a non-linguistic analysis section 107A and a voice controlsection 109B in addition to the construction shown in FIG. 1.

The non-linguistic analysis section 107A performs volume analysis andfrequency analysis on a voice signal of the remark, detected as a voiceutterance section by the section 104, to thereby detect pitch variationover time in the remark, and it outputs, as non-linguistic informationin the data indicative of the pitch variation in the remark. The dataindicative of the pitch variation is supplied to the voice controlsection 109B and the reply creation section 110.

The reply creation section 110 creates a reply corresponding to theremark analyzed by the linguistic analysis section 108, by use of thedata indicative of the pitch variation analyzed by the non-linguisticanalysis section 107A and with reference to the reply database 124 andthe information acquisition section 126. As in the eighth embodiment,the reply creation section 110 in the ninth embodiment may create(acquire) the following types of reply:

(1) reply indicative of an affirmative meaning;

(2) reply indicative of a negative meaning;

(3) reply of specific content to a question; and

(4) reply as back-channel feedback to the question (see FIGS. 22 to 24).

A voice sequence created/acquired by the reply creation section 110 issupplied to the voice control section 109B and the voice synthesissection 112, as in the above-described eighth embodiment (see FIG. 20etc.). The voice control section 109B determines content of control tobe performed on the voice sequence, in accordance with pitch datasupplied from the pitch analysis section 106 and data indicative ofpitch variation in the remark supplied form the non-linguistic analysissection 107A.

FIG. 28 is a flow chart of voice synthesis processing performed in theninth embodiment of the voice synthesis apparatus 10. FIG. 28 is shownas a modification of FIG. 4, and steps that perform substantially thesame operations as those in FIG. 4 are depicted by the same referencenumerals as in FIG. 4 and will not be described to avoid unnecessaryduplication.

At steps Sa13 a and Sa13 b of FIG. 28, the pitch analysis section 106analyzes the voice signal, in the detected utterance section, of thequestion (or remark), identifies a pitch of the first segment (wordending) in the question (or remark) and then supplies pitch dataindicative of the identified pitch to the voice synthesis section 112,in the same manner as at step Sa13 of FIG. 4. Namely, as step Sa13 a,the pitch analysis section 106 analyzes the voice signal in the detectedutterance section to convert the signal into waveforms separately forthe volume and pitch of the question (or remark). Examples of suchconverted volume waveform and pitch waveform are similar to those shownin FIG. 5 above. However, for convenience of explanation, the convertedvolume waveform and pitch waveform similar to those shown in FIG. 5 areshown in FIG. 29.

At step Sa26, the non-linguistic analysis section 107A identifies atimewise pitch variation state in the pitch waveform of the input voice(remark or question) analyzed at step Sa13 a above by the pitch analysissection 10. An example method for identifying such a timewise pitchvariation at step Sa26 will now be described with reference to FIG. 29.First, the non-linguistic analysis section 107A identifies, from thepitch waveform of FIG. 29(b), a pitch NO at a time point P0 that is apredetermined time Ts (e.g., 0.3 sec) before a time point of a localmaximum P1 of the volume waveform of FIG. 29(a). Then, thenon-linguistic analysis section 107A evaluates a pitch variation amountfrom the pitch N0 to a pitch N1 (i.e., N1−N0) and supplies this pitchvariation amount to the voice control section 109B and the replycreation section 110 as data indicative of a pitch variation state. Thetime Ts may be set as a variable value corresponding to a time intervalbetween the word beginning and ending of the remark, rather than beingset at a predetermined fixed value. As an example, a time pointcorresponding to the word beginning of the remark may be set as the timepoint P0. Further, content of the data indicative of a pitch variationstate to be identified by the non-linguistic analysis section 107A isnot limited to the pitch variation amount equal to the difference N1−N0.For example, a variation pattern of pitches of individual words(word-specific pitches) in the remark may be identified, and dataindicative of the thus-identified variation pattern may be supplied tothe voice control section 109B and the reply creation section 110 as thedata indicative of a pitch variation state.

Referring back to FIG. 28, operations similar to step Sa15 of FIG. 4 orsteps Sa15 a and Sa15 b of FIG. 21 are performed at steps Sa15 a andSa15 b of FIG. 28. However, in the ninth embodiment, the reply creationsection 110 is constructed in such a manner that, even for a remark(input voice) comprising a same character train, it can create a replycomprising a different character train in accordance with a pitchvariation state of the remark (input voice) as long as the pitchvariation state differs. For example, even where a result of linguisticanalysis of a remark uttered by the user is “asu wa hare”, the remarkcan become a question (interrogative sentence) “asu wa hare (desuka)?”(romanized Japanese meaning “Will it be fine tomorrow?” if the pitch ofthe remark rises toward the word ending. Thus, the reply creationsection 110 accesses the external server to acquire weather informationnecessary for a reply and outputs a voice sequence “hai” (romanizedJapanese meaning “yes”) if the acquired weather information indicates“hare” (romanized Japanese meaning “fine”) or outputs a voice sequence“iie” (romanized Japanese meaning “no”) if the acquired weatherinformation indicates other than “hare”. Further, even where the resultof linguistic analysis of the user's remark is “asu wa hare” as above,the remark can become a monologue like “asu wa hare (kâ)” if the pitchvariation of the remark is flat or falls toward the word ending. Thus,the reply creation section 110 reads out or outputs from the replydatabase 124 a voice sequence of back-channel feedback like “soudesune”. For example, the reply creation section 110 determines that thepitch of the remark rises toward the word ending if the pitch variationamount exceeds a threshold value, but determines that the pitch of theremark is flat or falls toward the word ending if the pitch variationamount is equal to or smaller than the threshold value.

At step Sa16 of FIG. 28, the voice control section 109B identifies apitch (initial pitch) of the word ending of the voice sequence suppliedfrom the reply creation section 110, in the same manner as step Sa16 ofFIG. 4.

Then, at step Sa17 a, the voice control section 109B determines contentof a change to be made to the pitch of the voice sequence as follows onthe basis of the pitch data and the data indicative of the pitchvariation state supplied from the non-linguistic analysis section 107A.More specifically, if the pitch of the user's remark rises toward theword ending, the voice control section 109B determines that the pitchesof the entire voice sequence be changed in such a manner that theinitial pitch of the word ending defined in the voice sequence assumes apredetermined interval relationship of five degrees down from the pitchindicated by the pitch data. If, on the other hand, the pitch of theuser's remark is flat or falls toward the word ending, the voice controlsection 109B determines that all of the pitches of the entire voicesequence be changed to the pitch five degrees down from the pitchindicated by the pitch data.

The following describe, in relation to a specific example, the pitchesof the remark, pitch variation and voice sequence change performed inthe ninth embodiment. A left area of FIG. 30(b) shows an example remarkgiven by the user, which more particularly shows an example where aresult of linguistic analysis of the user's remark is “asu wa hare”(romanized Japanese meaning “ ” It will fine tomorrow.” and where, persound (syllable), a pitch is indicated by a note as shown in the part.Note that, although the remark has a pitch waveform as shown in FIG.29(b), the pitch of the remark are depicted by the notes for convenienceof description. Because the pitch of the remark rises toward the wordending in the illustrated example, the reply creation section 110determines that the user's remark is a question (interrogativesentence). Thus, the reply creation section 110 outputs a voice sequence“hai” if weather information acquired in response to the remarkindicates “hare” or outputs a voice sequence “iie” if the acquiredweather information indicates other than “hare”.

FIG. 30(a) shows an example of fundamental voice of a voice sequence ofa reply “hai” (romanized Japanese), where a note is allocated per sound(syllable) to define a pitch and generation timing of each word(syllable or phoneme) of the fundamental voice.

Such a fundamental replying voice sequence is changed as follows by thevoice control section 109B. Namely, if, of the remark indicated in theleft area of FIG. 30(b), the pitch of the segment “re” at the wordending indicated by reference character A is indicated as “G” by thepitch data, the voice control section 109B changes the pitches of theentire voice sequence in such a manner that, of the reply “hai”, thepitch of the segment “i” at the word ending indicated by referencecharacter B becomes five degrees down from the pitch “G”. Whereas thevoice sequence change has been described in relation to the reply “hai”,pitches of entire voice sequences of other replying voices are changedin a similar manner to the aforementioned.

Where the result of the linguistic analysis of the user's remark is “asuwa hare” as above and the pitch variation of the remark is flat as shownin a left area of FIG. 31(b), the reply creation section 110 determinesthat the remark is a monograph or the like. Thus, the reply creationsection 110 outputs a voice sequence of for example, “sou desune”(romanized Japanese meaning “Well, . . . ”) as noted earlier. FIG. 31(a)shows an example of fundamental voice of the voice sequence of “soudesune”. Such a fundamental voice sequence is changed as follows by thevoice control section 109B.

Namely, if, of the remark indicated in the left area of FIG. 31(b), thepitch of the segment “re” at the word ending indicated by referencecharacter A is indicated as “G” by the pitch data, the voice controlsection 109B changes all the pitches of the replying voice “sou desune”(including “ne” at the word ending indicated by reference character B)to “C” that is five degrees down from “G” (see a right half area of FIG.31(b)).

In this case too, because voice of the reply is synthesized so that thepitch of the word ending of the reply as back-channel feedback assumes arelationship of five degrees down from the pitch of the word ending, itis possible to give the user a good impression as if a dialogue werebeing conducted with a person, without giving the user an unnaturalfeel. Further, according to the instant embodiment, even for the sameresult of the linguistic analysis of the remark, different replies arecreated depending on the pitch variation toward the word ending in theremark. Further, if the pitch of the remark is flat, the pitch ofback-channel feedback to the remark too is flattened; namely, the pitchvariation state defined in the original voice sequence too is changed.Thus, the instant embodiment can give the user an impression as if theuser were dialoging with a person rather than with a machine.

<Modification Using Voice Waveform Data>

Like the above-described eighth embodiment, the ninth embodiment may bemodified in a similar manner to the above-described second embodiment.Namely, the combination of the reply creation section 110 and the voicesynthesis section 112 of FIG. 27 (i.e., the voice generation sectionusing the voice synthesis technique) may be replaced with thecombination of the replying voice output section 113 and thepost-processing section 114 as shown in FIG. 8 or 16 or 19 (i.e., thevoice generation section using waveform data), and voice waveform data,for example, in the WAV format may be output from the replying voiceoutput section 113.

<Pitch Variation State of Reply, Average Pitch Etc. Of Reply>

The ninth embodiment has been described above as constructed to changethe pitch variation state and average pitch of the reply defined in theoriginal voice sequence as a result of shifting the pitches of theentire voice sequence so that the pitch of the word ending or the likeof the reply becomes, for example, five degrees down from the pitch ofthe word ending or the like of the question or as a result of flatteningthe pitches of the voice sequence. However, the ninth embodiment is notlimited to such a construction and may be modified to change the pitchvariation state of the fundamental voice sequence. For example, for thepitch variation state where the pitch of the remark rises toward theword ending, the ninth embodiment may change the pitch variation stateof the fundamental voice sequence so that the pitch of the reply fallstoward the word ending, while, for the pitch variation state where thepitch of the remark falls toward the word ending, the ninth embodimentmay change the pitch variation state of the fundamental voice sequenceso that the pitch of the reply rises toward the word ending. Further,the ninth embodiment may be constructed to change all or a portion ofthe pitches of the fundamental voice sequence so that the average pitchof the entire reply changes in accordance with the pitch of the wordending or the like of the remark or pitch variation of the remark.

<Volume and Volume Variation of Remark, and Volume and Volume Variationof Reply>

The ninth embodiment has been described above as constructed to identifythe word ending of the remark by use of volume variation of the remark.For such volume of the remark, various applications are conceivable asnon-linguistic information other than pitch information. For example,the ninth embodiment may be constructed to control volume of synthesizedvoice of the reply in accordance with an average volume of the remark.Further, the ninth embodiment may be constructed to control volumevariation of the reply in accordance with volume variation (amplitudeenvelope) of the remark.

<Content of Dialogue>

The ninth embodiment has been described above as constructed toterminate its processing at a time point when the voice synthesisapparatus 10 outputs a reply to the user's remark in synthesized voice.However, in an actual dialogue between persons, a remark and a reply areoften repeated instead of the dialogue merely ending with the remark andthe reply to the remark, and the number of such repetitions increases ordecreases depending on the meanings of the remark and the reply. Thus,as shown in FIG. 32, the ninth embodiment may be modified in such amanner that the linguistic analysis section 108 performs linguisticanalysis on not only the user's remark but also the reply created by thereply creation section 110 and supplies results of the linguisticanalysis to the voice control section 109, and that the voice controlsection 109 controls the pitch of the word ending or the like of thereply, pitch variation state of the reply, average pitch of the reply,etc. in accordance with the results of the linguistic analysis.

Note that the various application examples and/or the modificationsrelated to the first and second embodiments are also applicable to theninth embodiment of the present invention.

In summary, the above-described ninth embodiment is characterized byincluding: the non-linguistic analysis section (107A) that analyzespitch variation in the remark; and the control section (voice controlsection 109B) that performs, in accordance with the analyzed pitchvariation in the remark, control for changing the pitch of the voice ofthe reply generated by the voice generation section (the voice synthesissection 112, or the combination of the replying voice output section(113) and the post-processing section (114)).

<Tenth Embodiment>

The following describe, with reference to FIG. 33, a tenth embodiment ofthe voice synthesis apparatus of the present invention, which ischaracterized by modifying, in accordance with an attribute of a speakeror utterer of a remark or an attribute of replying voice, a rule fordetermining a pitch of the second segment in the replying voice. FIG. 33is a functional block diagram of the tenth embodiment of the voicesynthesis apparatus 10 of the present invention. Blocks in FIG. 33 thatimplement substantially the same functions as those in FIG. 1 aredepicted by the same reference characters as in FIG. 1 and will not bedescribed to avoid unnecessary duplication. The embodiment of FIG. 33includes a voice control section 109C in addition to the constructionshown in FIG. 1.

Similarly to the counterpart in each of the above-described embodiments,the voice synthesis section 112 in the tenth embodiment synthesizesvoice of the reply by controlling the pitch of the second segment of thereply in accordance with a given rule, i.e. in such a manner that thepitch of the second segment of the reply assumes a predeterminedinterval relationship with the pitch of the word ending of the questionor remark. Further, the voice synthesis section 112 in the tenthembodiment is constructed to generate voice of the reply with acharacteristic based on a given agent attribute. The agent attribute isinformation indicative of a virtual person whose voice is to besynthesized by the voice synthesis apparatus 10. Namely, the agentattribute is data indicative of the person for defining what type ofperson is assumed to synthesize the voice of the reply. For simplicityof description, let it be assumed here that the agent attribute is datadefining a sex. The instant embodiment is constructed in such a mannerthat a desired agent attribute is selected or set by the user via anoperation input section belonging to the voice synthesis apparatus 10,and that information indicative of the selected or set agent attributeis supplied to the voice synthesis section 112 and voice of the reply issynthesized with a characteristic based on the agent attribute.

The aforementioned rule to be applied in the voice synthesis section 112in order to control the pitches of the replying voice sequence isdetermined by the voice control section 109C. As an example default ofthe rule (default rule), it is defined that the voice control section109C should shift the pitch of the word ending of the reply to assume apredetermined interval relationship with, more specifically five degreesdown from, the pitch of the word ending of the remark (question). In analternative, however, the voice control section 109C may shift the pitchof the word ending of the reply to a pitch that has other than theabove-mentioned interval relationship of five degrees down from thepitch of the word ending of the remark (question). However, if thedefault rule is adhered to, the reply created through voice synthesismay undesirably become unnatural. Thus, the voice control section 109Cis constructed to modify as necessary the default rule in accordancewith the attribute of the remark utterer (remark utterer's attribute)and the agent attribute, so that the rule to be applied in the voicesynthesis section 112 is determined. The remark utterer's attribute isan attribute of the utterer of the input remark (question), which is, inthe instant embodiment, the sex of the utterer (user). As data definingthe remark utterer's attribute can be used, for example, personalinformation of the user registered in the terminal apparatus functioningas the voice synthesis apparatus 10.

For voice synthesis, the voice synthesis section 112 uses voice fragmentdata registered in the voice library 128. Voice fragment data definingwaveforms of various voice fragments, such as individual phonemes andphoneme-to-phoneme transition portions, that are to be used as materialsof voices are compiled in advance as a database for each of a pluralityof agent attributes. More specifically, the voice synthesis section 112generates a voice signal using the voice fragment data defined by theselected or set agent attribute, more specifically by combining thevoice fragment data of individual sounds (syllables) of a voice sequenceand modifying the combined voice fragment data to be connectedcontinuously.

FIG. 34 is a flow chart of a process performed in the tenth embodimentof the voice synthesis apparatus 10. FIG. 34 is shown as a modificationof FIG. 4, and steps that perform substantially the same operations asthose in FIG. 4 are depicted by the same reference numerals as in FIG. 4and will not be described to avoid unnecessary duplication.

Operations similar to step Sa15 of FIG. 4 and steps Sa15 a and Sa15 b ofFIG. 21 are performed at steps Sa15 a and Sa15 b of FIG. 34. Further, atstep Sa16, an operation for identifying a pitch (initial pitch) of theword ending in the replying voice sequence, in the same manner as atstep Sa16 of FIG. 14. Further, at step Sa13, analysis is performed onthe voice signal of the remark in the detected utterance section toidentify a pitch of the first segment (word ending) in the remark, inthe same manner as at step Sa13 of FIG. 14. Pitch data indicative of thethus-identified pitch is supplied to the voice control section 19C.

At step Sa27, a rule determination process is performed by the voicecontrol section 109C, on the basis of the agent attribute and the remarkutterer's attribute, to determine a rule to be applied. FIG. 35 is aflow chart showing details of the rule determination process.

First, at step Sb11 of FIG. 35, the voice control section 109C acquiresdata indicative of the agent attribute and data indicative of the agentattribute. Then, at step Sb12, the voice control section 109Cdetermines, on the basis of the acquired data, whether or not the remarkutterer's attribute, i.e. the user's attribute, is female. If the remarkutterer's attribute is female (Yes determination at step Sb12), thevoice control section 109C modifies the default rule such that the pitchof the word ending of the reply is shifted to a pitch six degrees (notdefault five degrees) down from the pitch indicated by the pitch data,i.e. to a pitch that is in a consonant interval relationship with thepitch indicated by the pitch data and one rank down from the defaultrelationship, with the pitch indicated by the pitch data. In thismanner, a pitch lowered from the pitch preset by the default rule isdetermined as the pitch of the word ending of the reply, at step Sb13.The term “rank” does not have any musical meaning and is used hereinmerely for convenience of description. Namely, in the instantembodiment, where the pitch five degrees down from the pitch indicatedby the pitch data is set as a reference pitch, the pitch lowered by onerank from the reference pitch refers to a pitch that is six degrees(major sixth) down from the pitch indicated by the pitch data, and thepitch lowered by another one rank from the reference pitch refers to apitch that is eight degrees down from the pitch indicated by the pitchdata. Further, the pitch raised by one rank from the reference pitchrefers to a pitch that is three degrees (major third) up from (higherthan) the pitch indicated by the pitch data, and the pitch raised byanother one rank from the reference pitch refers to a pitch that is fourdegrees up from the pitch indicated by the pitch data.

If, on the other hand, the remark utterer's attribute is not female (Nodetermination at step Sb12), the voice control section 109C furtherdetermines, at step Sb14, whether the remark utterer's attribute ismale. If the remark utterer's attribute is male (Yes determination atstep Sb14), the voice control section 109C modifies the default rulesuch that the pitch of the word ending of the reply is shifted to apitch three degrees down from the pitch indicated by the pitch data. Inthis manner, a pitch raised from the pitch preset by the default rule isdetermined as the pitch of the word ending of the reply, at step Sb15.If the remark utterer's attribute is neutral or if the remark utterer'sattribute has not yet been registered (No determination at step Sb14),the voice control section 109C skips the operation at step Sb13 or Sb15and uses the default rule in an unmodified form.

Then, at step Sb16, the voice control section 109C determines whether ornot the agent attribute is female. If the agent attribute is female (Yesdetermination at step Sb16), the voice control section 109C modifies themodified default rule (or unmodified default rule) such that the pitchof the word ending of the reply is shifted one rank up, at step Sb17.For example, if the default rule has been modified at step Sb13 abovesuch that the pitch of the word ending of the reply is shifted one rankdown, or six degrees down from the pitch indicated by the pitch data,the voice control section 109C returns the modified rule back to theoriginal default rule at step Sb17 such that the pitch of the wordending of the reply is shifted five degrees down from the pitchindicated by the pitch data. Further, if the default rule has beenmodified at step Sb15 above at step Sb17 such that the pitch of the wordending of the reply is shifted one rank down, or three degrees down fromthe pitch indicated by the pitch data, the voice control section 109Cfurther modifies the modified default rule at step Sb17 such that thepitch of the word ending of the reply is shifted one further rank up, orfour degrees up from the pitch indicated by the pitch data. Note that,if the operation of step Sb13 or Sb15 has been skipped as above, thevoice control section 109C modifies the default rule at step Sb17 suchthat the pitch of the word ending of the reply is shifted one rank up,or three degrees down from the pitch indicated by the pitch data.

If the agent attribute is not female (No determination at step Sb16),the voice control section 109C further determines, at step Sb18, whetherthe agent attribute is male. If the agent attribute is male (Yesdetermination at step Sb18), the voice control section 109C furthermodifies the modified default rule such that the pitch of the wordending of the reply is shifted up to the pitch that is one rank down, atstep Sb19. For example, if the default rule has been modified such thatthe pitch of the word ending of the reply is shifted one rank down orsix degrees down from the pitch indicated by the pitch data, the voicecontrol section 109C further modifies the default rule at step Sb19 suchthat the pitch of the word ending of the reply is shifted to the pitchone further rank down from the reference pitch or eight degrees downfrom the pitch indicated by the pitch data. Further, if the default rulehas been modified such that the pitch of the word ending of the reply isshifted to the pitch one rank up or three degrees down from the pitchindicated by the pitch data, the voice control section 109C returns themodified default rule back to the original default rule such that thepitch of the word ending of the reply is shifted to the pitch that isfive degrees down as originally defined. Further, if the operation ofstep Sb13 or Sb15 has been skipped, the voice control section 109Cmodifies the default rule at step Sb19 so that the pitch of the wordending of the reply is shifted to the pitch that is one rank down fromthe reference pitch or six degrees down from the pitch indicated by thepitch data.

If the agent attribute is neutral or if the agent attribute has not yetbeen registered (No determination at step Sb18), the voice controlsection 109C skips the operation at step Sb17 or Sb19. After completionof the operation at step Sb17 or Sb19, or after the skipping of stepSb17 or Sb19, the process reverts to step Sa28 of FIG. 34. The rule tobe applied is determined by the default rule being modified asappropriate. Note that the modification of the default rule, i.e. thedetermination of the rule, may be performed on the basis of at least oneof the agent attribute and the remark utterer's attribute.

Referring back to FIG. 34, the voice control section 109C determines atstep Sa28 that the voice sequence supplied from the reply creationsection 110 be changed by applying the rule determined at step Sa27 (orthe default rule). More specifically, if the determined rule definesthat the pitch of the word ending in the reply should be shifted to apitch that is, for example, three degrees down from the pitch indicatedby the pitch data, the voice control section 109C shifts all the pitchesof voice sequence in such a manner that the pitch of the word ending inthe reply defined in the voice sequence supplied from the reply creationsection 110 assumes an interval relationship of three degrees down fromthe pitch indicated by the pitch data. At step Sa18, the voice controlsection 109C controls the voice synthesis by the voice synthesis section112 in accordance with the determined content. Thus, the voice synthesissection 112 controls the pitches of the voice sequence in accordancewith the rule determined by the voice control section 109C and therebysynthesizes and outputs a replying voice signal having the controlledpitches.

The following describe pitches of a remark, fundamental pitches of avoice sequence and pitches of a changed voice sequence in relation tosome specific examples. A left area of FIG. 36(b) shows an example of aremark uttered by the user. In the illustrated example of FIG. 36, aresult of linguistic analysis of the remark is “asu wa hare desuka?”(romanized Japanese meaning “Will it be fine tomorrow?”) and wherepitches are allocated to individual sounds of the remark by notes asshown in the left area. Although the remark has in reality a pitchwaveform similar to that shown in FIG. 5(b), the pitches of the remarkare depicted by notes for convenience of explanation. In this case, thereply creation section 110 outputs a voice sequence “hai” if weatherinformation acquired in response to the remark indicates “hare” oroutputs a voice sequence “iie” if the acquired weather informationindicates other than “hare”, in the same manner as set forth above.

FIG. 36(a) shows an example of fundamental pitches of the voice sequence“hai” (romanized Japanese), and a right area of FIG. 36(b) shows anexample of a replying voice sequence controlled in pitch in accordancewith the default rule. Namely, if the default rule is to be applied, thevoice sequence output by the reply creation section 110 is changed bythe voice control section 109C as follows. Namely, if, of the remarkindicated in the left area of FIG. 36(b), the pitch of the segment “ka”at the word ending indicated by reference character A is indicated as“E” by the pitch data, the voice control section 109C changes thepitches of the entire voice sequence so that, of the reply “hai”, thepitch of the segment “i” at the word ending indicated by referencecharacter B becomes the pitch “A” that is five degrees down from thepitch “E” (see the right area of FIG. 36(b)).

Note that, in the instant embodiment, the default rule is applied inthree cases: when a “No” determination has been made at each of stepsSb12, Sb14, Sb16 and Sb18; a “Yes” determination has been made at stepSb12 and a “Yes” determination has been made at step Sb16; and when a“No” determination has been made at step Sb12 and a “Yes” determinationhas been made at step Sb14, and a “Yes” determination has been made atstep Sb18.

Where the remark has been uttered as shown in the left area of FIG.36(b) and if the modified rule instructing a shift to a pitch that isfor example six degrees down from the pitch indicated by the pitch datais to be applied, the voice sequence output by the reply creationsection 110 is changed by the voice control section 109C as follows.Namely, the voice control section 109C changes the pitches of the entirevoice sequence so that, of the reply “hai”, the pitch of the segment “i”at the word ending indicated by reference character B is changed to thepitch “G” six degrees down from the pitch “E” (see a right area of FIG.37).

Note that, in the instant embodiment, the rule instructing “six degreesdown” is applied in two cases: when a “Yes” determination has been madeat step Sb12, and a “No” determination has been made at steps Sb16 andSb18; and when a “No” determination has been made at steps Sb12 andSb14, a “No” determination has been made at step Sb16, and a “Yes”determination has been made at step Sb18.

Where the remark has been uttered as shown in the left area of FIG.36(b) and if the modified rule instructing a shift to a pitch that isfor example eight degrees down from the pitch indicated by the pitchdata is to be applied, the voice sequence output by the reply creationsection 110 is changed by the voice control section 109C as follows.Namely, the voice control section 109C changes the pitches of the entirevoice sequence so that, of the reply “hai”, the pitch of the segment “i”at the word ending indicated by reference character B is changed to thepitch “E” eight degrees (one octave) down from the pitch “E” (see aright area of FIG. 38). Note that, in the instant embodiment, the ruleinstructing “eight degrees down” is applied only in one case, i.e. whena “Yes” determination has been made at step Sb12, a “No” determinationhas been made at step Sb16 and a “Yes” determination has been made atstep Sb18.

Where the remark has been uttered as shown in the left area of FIG.36(b) and if the modified rule instructing a shift to a pitch threedegrees down from the pitch indicated by the pitch data is to beapplied, the voice sequence output by the reply creation section 110 ischanged by the voice control section 109C as follows. Namely, the voicecontrol section 109C changes the pitches of the entire voice sequence sothat, of the reply “hai”, the pitch of the segment “i” at the wordending indicated by reference character B is changed to the pitch “C”three degrees down from the pitch “E” (see a right area of FIG. 39).Note that, in the instant embodiment, the rule instructing “threedegrees down” is applied in two cases: when a “No” determination hasbeen made at step Sb12, a “Yes” determination has been made at step Sb14and a “No” determination has been made at steps Sb16 and Sb18 Sb; andwhen a “No” determination has been made at steps Sb12 and Sb14 and a“Yes” determination has been made at step Sb16.

Where the remark has been uttered as shown in the left area of FIG.36(b) and if the modified rule instructing a shift to a pitch foursdegrees up from the pitch indicated by the pitch data is to be applied,the voice sequence output by the reply creation section 110 is changedby the voice control section 109C as follows. Namely, the voice controlsection 109C changes the pitches of the entire voice sequence so that,of the reply “hai”, the pitch of the segment “i” at the word endingindicated by reference character B is changed to the pitch “A” fourdegrees up from the pitch “E” (see a right area of FIG. 40). Note that,in the instant embodiment, the rule instructing “four degrees up” isapplied in only one case. i.e. when a “No” determination has been madeat step Sb12, a “Yes” determination has been made at step Sb14 and a“Yes” determination has been made at step Sb16.

The instant embodiment has been described above in relation to the casewhere the reply comprises a word “hai”. However, for other repliescomprising other words than “hai” as well, the pitches of the entirereply voice sequence are changed in accordance with the rule determinedon the basis of at least one of the agent attribute and the remarkutterer's attribute in a similar manner to the aforementioned.

In the case where the default rule defining that the pitch of the wordending of the reply should be five degrees down from the pitch of theword ending of the remark is applied, voices of the reply aresynthesized in the instant embodiment in such a manner that the pitch ofthe word ending of the reply is lowered by one rank if the utterer'sattribute is female but raised by one rank if the utterer's attribute ismale. Further, in the case where the default rule defining that thepitch of the word ending of the reply should be five degrees down fromthe pitch of the word ending of the remark is applied, voices of thereply are synthesized in the instant embodiment so that the pitch of theword ending of the reply is raised by one rank if the agent attribute isfemale but lowered by one rank if the utterer's attribute is male.Because the pitches of the reply are changed in accordance with theutterer's attribute and the agent attribute as above, the instantembodiment can give the user a kind of freshness and joy.

<Modification Using Voice Waveform Data>

Like the above-described eighth embodiment and ninth embodiment, thetenth embodiment may be modified in a similar manner to theabove-described second embodiment. Namely, the combination of the replycreation section 110 and the voice synthesis section 112 (i.e., thevoice generation section using the voice synthesis technique) may bereplaced with the combination of the replying voice output section 113and the post-processing section 114 as shown in FIG. 8 or 16 or 19(i.e., the voice generation section using waveform data), and voicewaveform data for example in the WAV format may be output from thereplying voice output section 113.

<Utterer's Attribute>

The tenth embodiment has been described above as using, as the utterer'sattribute, user's personal information registered in the terminalapparatus functioning as the voice synthesis apparatus 10. In analternative, however, an utterer's attribute may be detected in thevoice synthesis apparatus 10. For example, volume analysis, frequencyanalysis, etc. may be performed on a user's remark, and then such ananalyzed user's remark may be compared against patterns corresponding tocombinations of prestored various sexes and ages so that an attribute ofan one of the patterns that has a high degree of similarity is detectedas the utterer's attribute. If no such utterer's attribute could not bedetected, a “No” determination is made at steps Sb12 and Sb14 of FIG.35.

<Agent Attribute>

Whereas the tenth embodiment has been described above in relation to thecase where the agent attribute is sex, the agent attribute may comprisea combination of three or more attributes, such as sex, age, etc.

<Repetition of Back-channel Feedback, Output Timing of Back-channelFeedback, Etc.>

When a dialogue between persons is viewed from the perspective of thesex of an utterer, the following particular tendency might be seendepending on the utterer's attribute. Let it be assumed, for convenienceof description, that females generally have a tendency of laying weighton atmosphere and harmony and a tendency of livening up the atmosphereare seen in the dialogue. More specifically, let it be assumed thattendencies of frequently using back-channel feedback, repeatingback-channel feedback, shortening a time length from a remark to areply, etc. are seen. Let it be further assumed that females must expectsuch tendencies also from the voice synthesis apparatus 10 that outputsa reply to the remark in synthesized voice. Thus, if the utterer'sattribute is female, the voice control section 109C may inform the replycreation section 110 to that effect so that the reply creation section110 increases a frequency at which replies are created as back-channelfeedback to the remark or repetitively outputs a voice sequence of thesame back-channel feedback. Further, the voice control section 109C maycontrol the voice synthesis section 112 to relatively speed up a timefrom the end of the user's remark to a time point when output of a replyto the remark is started.

On the other hand, males may generally have a tendency of laying weighton content, logicality, individuality, etc. in a dialogue. Morespecifically, let it be assumed, for convenience of description, thatmales have tendencies of not giving back-channel feedback more thannecessary, daring to give no reply (daring to be silent) depending onthe situation, lengthening a time length from a remark to a reply, etc.Thus, if the utterer's attribute is male, the voice control section 109Cmay inform the reply creation section 110 to that effect so that thereply creation section 110 lowers the frequency at which replies arecreated as back-channel feedback to the remark and sometimes gives noreply with a predetermined probability. Further, the voice controlsection 109C may control the voice synthesis section 112 to relativelyslow down a time from the end of the user's remark to a time point whenoutput of a reply to the remark is started.

Further, as a condition to be applied when the pitch of the word endingof the reply is to be lowered from the pitch predetermined in accordancewith the default rule, a condition that the pitch of the word ending ofthe remark should be equal to or greater than the first threshold pitch(frequency) may be added at step Sb13 of FIG. 35 (see mark in the blockof step Sb13) to the condition that the utterer's attribute is female.This is for the purpose of avoiding the reply, comprising synthesizedvoice, becoming unnaturally high in a case where the remark made by thefemale is high in pitch. Similarly, as a condition to be applied whenthe pitch of the word ending of the reply is to be raised from the pitchpredetermined in accordance with the default rule, a condition that thepitch of the word ending of the remark should be equal to or smallerthan the second threshold pitch may be added at step Sb15 of FIG. 35(see mark in the block of step Sb15) to the condition that the utterer'sattribute is male. This is for the purpose of avoiding the reply,comprising synthesized voice, becoming unnaturally low in a case wherethe remark made by the male is low in pitch.

Note that the various application examples and/or the modificationsrelated to the first and second embodiments are also applicable to thetenth embodiment of the present invention.

In short, the above-described tenth embodiment is characterized in thatthe voice generation section (i.e., the voice synthesis section 112 orthe combination of the replying voice output section 113 and thepost-processing section 114), is constructed to associate the pitch ofthe second segment with the analyzed pitch of the first segment inaccordance with a given rule and generate voice of the reply with acharacteristic based on a given agent attribute. The tenth embodimentfurther includes the control section (voice control section 109C) thatdetermines the above-mentioned rule on the basis of at least one of theagent attribute and the attribute of the utterer of the remark.

<Eleventh Embodiment>

The following describe, with reference to FIG. 41, an eleventhembodiment of the voice synthesis apparatus of the present invention,which is characterized in that the rule for associating the pitch of thesecond segment of the replying voice with the analyzed pitch of thefirst segment is updated, after audible generation or sounding of thereplying voice, in response to voice of a further remark being receivedvia the voice input section. Namely, the eleventh embodiment ischaracterized by changing as appropriate the rule to be applied togeneration of next replying voice, in view of a further remark utteredby the user in response to the reply uttered by the machine. FIG. 41 isa functional block diagram of the eleventh embodiment of the voicesynthesis apparatus 10 of the present invention. Blocks in FIG. 41 thatimplement substantially the same functions as those in FIG. 1 aredepicted by the same reference characters as in FIG. 1 and will not bedescribed to avoid unnecessary duplication. The embodiment of FIG. 41includes a voice control section 109D and a managing database 127 inaddition to the construction shown in FIG. 1.

Similarly to the counterpart in each of the above-described embodiments,the voice synthesis section 112 in the eleventh embodiment synthesizesvoice of the reply by controlling the pitches of the replying voicesequence, created by the reply creation section 110, in accordance witha given rule (i.e., such that the pitch of the second segment of thereply assumes a predetermined interval relationship with the pitch ofthe first segment of the question or remark). The given rule employed inthe eleventh embodiment will hereinafter be referred to as “pitch rule”.The voice control section 109D controls the voice synthesis by the voicesynthesis section 112 by updating the rule (pitch rule), applied to thevoice synthesis section 112, after audible generation or sounding of thereplying voice, in response to voice of a further remark being receivedvia the voice input section 102.

What kind of relationship the pitch of the second segment of the replyshould assume with respect to the pitch of the first segment of thequestion or remark in order to make the user feel comfortable and makethe dialogue lively differs from one user to another, as noted earlier.Thus, in the eleventh embodiment, an evaluation period is provided as anoperation period, and voice of replies to a same remark is synthesizedusing a plurality of pitch rules. Then, upon end of the evaluationperiod, one of the pitch rules which has achieved the liveliest dialogue(i.e., with which the dialog has been made liveliest) is set as thepitch rule to be applied, so that the thus-set pitch rule can bereflected in subsequent voice synthesis.

The managing database 127, which is managed by the voice control section109D, stores, among other things, a table (index table) where the pitchrules and indices indicative of degrees of liveliness of dialogue areassociated with each other in a one-to-one relationship. FIG. 42 is adiagram showing an example of stored content in the index table. Asshown in FIG. 42, the number of remarks and the number of applicationsare associated with each other for each of the pitch rules. Here, thepitch rules each define what kind of relationship the pitch of the wordending of the reply should have with respect to the pitch of the wordending of the reply, such as four degrees up, three degrees down, fivedegrees down, six degrees down and eight degrees down, as shown in thefigure.

Further, the “number of remarks” means a count of the number of remarksuttered by the user in a case where the voice synthesis apparatus 10synthesized voice of a reply to a remark uttered by the user and thenthe user has uttered a further remark within a predetermined timeperiod. Stated differently, during the evaluation period, even whenvoice of a reply has been synthesized by the voice synthesis apparatus10, it is conceivable that no further remark is uttered by the user or afurther remark, if any, is uttered after passage of the predeterminedtime period; such further remark is not counted as the number ofremarks. The “number of applications” means the number of times thecorresponding pitch rule has been applied during the evaluation period.Thus, by comparing values calculated by dividing the number of remarksby the corresponding number of applications, the user can know which oneof the pitch rules has achieved the greatest number of remarks to thereplies, i.e. which one of the pitch rules has achieved the liveliestdialogue. Note that, even when voice of a reply has been synthesizedthrough application of any one of the pitch rules, the user maysometimes utter no remark to that reply within the predetermined timeperiod. This is because the number of applications is greater than thenumber of remarks as in the illustrated example of FIG. 42.

FIG. 43 is a diagram showing an example of the operation period providedby the application program executed by the CPU. In the instantembodiment, as shown in FIG. 43, rule fixed periods and theabove-mentioned evaluation periods are repeated alternately in theoperation period. Here, the rule fixed period is a time period in whichvoice of a reply is synthesized in accordance with one pitch rule setupon end of the evaluation period. As an example, such a pitch rule setin one of the rule fixed periods is “five degrees down” as indicated bya white triangle in the figure.

The evaluation period is, on the other hand, is a time period forevaluating any one of the pitch rules which has achieved the liveliestdialogue on the basis of synthesizing voice of replies by applying thepitch rule to a remark uttered by the user. Whereas the instantembodiment is constructed so that the rule fixed periods and theabove-mentioned evaluation periods are repeated alternately in theoperation period as shown on FIG. 43, it may be constructed so as toshift to the evaluation period, for example, only in response to auser's instruction.

FIG. 44 is a flow chart of the voice synthesis processing performed inthe eleventh embodiment of the voice synthesis apparatus 10. This voicesynthesis processing is performed irrespective of the rule fixed periodand the evaluation period. FIG. 44 is shown as a modification of FIG. 4,and steps that perform substantially the same operations as those inFIG. 4 are depicted by the same reference numerals as in FIG. 4 and willnot be described to avoid unnecessary duplication.

Operations similar to step Sa15 of FIG. 4 or steps Sa15 a and Sa15 b ofFIG. 21 are performed at steps Sa15 a and Sa15 b of FIG. 44. At stepSa16 of FIG. 44, an operation is performed for identifying a pitch(initial pitch) of the second segment (word ending) in the voicesequence supplied from the reply creation section 110, in the samemanner as step Sa16 of FIG. 4. Further, at step Sa13 a of FIG. 44, thevoice signal, in the detected utterance section, of the remark isanalyzed to identify a pitch of the first segment (word ending) in theremark, in the same manner as at step Sa13 of FIG. 4. Then, dataindicative of the identified pitch is supplied to the voice controlsection 109D.

At step Sa29, the voice control section 109D determines whether thecurrent time point is in one of the rule-fixed periods. If the currenttime point is in one of the rule-fixed periods (Yes determination atstep Sa29), the voice control section 109D applies the pitch rule set inthe evaluation period preceding the rule-fixed period, at step Sa30. Ifthe current time point is not in one of the rule-fixed periods but inone of the evaluation periods (NO determination at step Sa29), the voicecontrol section 109D selects, for example, any one of a total of threepitch rules that are a pitch rule set in the evaluation period precedingthe current evaluation period and two pitch rules immediately upper anddown from (i.e., sandwiching in an up-down direction) the pitch rule inthe index table and then applies the thus-selected pitch rule, at stepSa31. More specifically, if the set pitch rule is “five degrees down”depicted by the white triangular mark in FIG. 42, the voice controlsection 109D selects, randomly or in a predetermined order, any one ofthe three pitch rules: the pitch rule of “five degrees down” and thepitch rules of “three degrees down” and “six degrees down” sandwiching“five degrees down” in a vertical or up-down direction in the indextable.

At next step Sa32, the voice control section 109D instructs the voicesynthesis section 112 to effect a pitch change on the reply such thatthe pitch of the second segment (word ending) of the reply assumes apredetermined interval relationship, defined by the applied pitch rule,with the pitch of the first segment (word ending) of the remarkidentified at step Sa13. In accordance with such an instruction, thevoice synthesis section 112 changes the pitches of the entire voicesequence in such a manner that the pitch of the word ending of the replyis shifted to the pitch defined by the applied pitch rule. In theinstant embodiment, the processing reverts to step Sa11 after one replyhas been output through the voice synthesis (i.e., in synthesizedvoice), in order to allow the user to make a further remark followingthe reply (i.e., in order to receive a further remark). If the user doesnot want to continue the dialogue with the machine, the instant voicesynthesis processing can be brought to an end in response to a user'sexplicit operation (e.g., user's operation of a software button).

FIG. 45 is a flow chart showing a table update process. This tableupdate process, which is performed independently of the voice synthesisprocessing of FIG. 44, is designed primarily to update the index table(see FIG. 42) in the evaluation period to thereby set a pitch rule to beapplied in the rule-fixed period.

At step Sb21, the voice control section 109D determines whether thecurrent time point (current time) is in one of the evaluation periods.If the current time point is not in one of the evaluation periods (Nodetermination at step Sb21), the voice control section 109D revers thetable update process to step Sb21. If, on the other hand, the currenttime point is in one of the evaluation periods (Yes determination atstep Sb21), the voice control section 109D further determines, at stepSb22, whether any reply created through voice synthesis by the voicesynthesis section 112 has been output or not. If no such reply has beenoutput (No determination at step Sb22), the voice control section 109Dreverts the table update process to step Sb21. Thus, no subsequentoperation in the table update process is performed unless the currenttime point is in one of the evaluation periods and any reply has beenoutput. If, on the other hand, a reply has been output (Yesdetermination at step Sb22), the voice control section 109D furtherdetermines, at step Sb23, whether or not there has been any remark ofthe user within a predetermined time period (e.g., 5 sec) after theoutput of the reply. Whether or not there has been any remark of theuser within the predetermined time period can be determined by the voicecontrol section 109D checking whether or not pitch data has beensupplied within the predetermined time period after the output of thereply.

If there has been any remark of the user within the predetermined timeperiod after the output of the reply (“Yes” determination at step Sb23),the voice control section 109D at step Sb24 identifies the pitch rulehaving been applied to the voice synthesis of the reply, with a view toupdating the index table. Identification of such a pitch rule ispermitted by, upon selection of a pitch rule, storing the selected pitchrule and selected time information into the managing database 127 inassociation with each other upon selection of the pitch rule at stepSa31 above and then searching for the pitch rule associated with thenewest or latest time information. At step Sb25, the voice controlsection 109D increments by “1” the items (the number of remarks and thenumber of applications) of the pitch rule, applied to the voicesynthesis of the reply, in the index table.

If, on the other hand, there has been no remark of the user within thepredetermined time period after the output of the reply or a remark hasbeen made after the passage of the predetermined time period (“No”determination at step Sb23), the voice control section 109D identifiesthe pitch rule having been applied to the voice synthesis of the replyat step Sb26, in the same manner as at step Sb24. In this case, however,the voice control section 109D at step Sb27 increments by “1” only thenumber of applications of the pitch rule, applied to the voice synthesisof the reply, in the index table, because it is regarded that there hasbeen no user's remark.

Next, at step Sb28, the voice control section 109D determines whetherthe current time point is end timing of the evaluation period. If thecurrent time point is not end timing of the evaluation period (“No”determination at step Sb28), the voice control section 109D reverts theprocess to step Sb21 above in order to prepare for a next time when theuser will make a remark after the output of the reply. If, on the otherhand, the current time point is end timing of the evaluation period(“Yes” determination at step Sb28), the voice control section 109Dcompares, in the evaluation period in question, the values calculatedfor the three pitch rules by dividing the number of remarks by thecorresponding number of applications, so that the voice control section109D sets, as the pitch rule to be applied in the rule-fixed periodfollowing the evaluation period, one of the pitch rules which hasachieved the liveliest dialogue (step Sb29). For example, if, in theoperation of step Sb28, the three pitch rules in the evaluation periodare three degrees down, five degrees down, six degrees down,respectively, and the number of remarks and the number of applicationsare of values as shown in FIG. 42, the pitch rule to be applied in therule-fixed period is changed from the previously-set “five degrees down”pitch rule to the “three degrees down” pitch rule depicted by a blacktriangular mark. After that, the voice control section 109D clears thenumber of remarks and the number of applications of each of the threepitch rules evaluated in the evaluation period (step Sb30) and thenreverts the process to step Sb21 in order to perform similar operationsin the next evaluation period.

As set forth above, the instant embodiment is constructed to: create areply by applying any one of the different pitch rules in the evaluationperiod, update the number of remarks and the number of applications ofthe applied pitch rule if there has been any user's remark to the replywithin the predetermined time period, and update only the number ofapplications of the applied pitch rule if the user's remark to the replyis not within the predetermined time period. Then, at the end timing ofthe evaluation period, the pitch rule which has achieved the liveliestdialogue is set and applied in the next rule-fixed period.

Specific examples of the pitch of the remark, fundamental pitches of thevoice sequence and changed pitches of the voice sequence in the eleventhembodiment may be similar to those shown in FIGS. 36 to 40. Namely, if“five degrees down” is applied as the rule for determining pitches ofthe reply “hai” to the remark “asu wa hare desuka?” as shown in the leftarea of FIG. 36(b), then a pitch pattern as shown in the right area ofFIG. 36(b) is provided. If “six degrees down” is applied as the rule,then a pitch pattern as shown in the right area of FIG. 37 is provided.Further, if “eight degrees down” is applied as the rule, then a pitchpattern as shown in the right area of FIG. 38 is provided. Further, if“three degrees down” is applied as the rule, then a pitch pattern asshown in the right area of FIG. 39 is provided. Furthermore, if “fourdegrees up” is applied as the rule, then a pitch pattern as shown in theright area of FIG. 40 is provided.

In the eleventh embodiment, the pitch rule to be applied in therule-fixed period is the pitch rule which has achieved the liveliestdialogue in the evaluation period preceding the rule-fixed period. Thus,in the rule-fixed period too, a dialogue can easily become lively;simply put, it becomes easy for the user to make a remark. Further,because such a pitch rule is set in each of the evaluation periods,there can be achieved conditions that are comfortable to the user, canrelax the user and can make a dialogue lively (i.e., can direct thedialogue in a livened-up direction).

<Twelfth Embodiment>

The eleventh embodiment has been described as constructed to apply aplurality of pitch rules in the evaluation period, set any one of thepitch rules which has achieved the liveliest dialogue and use thethus-set pitch rule in the rule-fixed period. However, examples offactors that can make a dialogue lively include, in addition to thepitch, a “pause”, i.e. a time interval, from a remark to a reply.Therefore, the following describe a twelfth embodiment of the presentinvention not only performs replying voice pitch control on the basis ofsetting of a pitch rule as in the eleventh embodiment, but also outputsreplies with different pauses in the evaluation period, sets one of thepauses that has achieved the liveliest dialogue and applies the thus-setpause to control a pause for a reply.

Functional blocks built in the twelfth embodiment through the executionof the above-mentioned application program are substantially similar tothose in the eleventh embodiment of FIG. 41. However, the twelfthembodiment uses, as index tables, a table for evaluating reply outputrules as shown in FIG. 46, in addition to a table for evaluating pitchrules as shown in FIG. 42.

In the index table for evaluating the reply output rules, as shown inFIG. 46, the number of remarks and the number of applications areassociated with each other for each of the output rules. Here, theoutput rules each define a pause or time interval, for example, from theend (word ending) of a remark to the start (word beginning) of a reply,and 0.5 sec, 1.0 sec, 1.5 sec. 2.0 sec and 2.5 sec are designated in astepwise manner by these output rules. Note that the numbers of remarksand the numbers of applications associated with the individual outputrules in the instant are similar to those in the eleventh embodiment.

Processing in the twelfth embodiment may be similar to the processingshown in FIGS. 44 and 45, except that “pitch rule” in FIGS. 44 and 45should be read as “pitch rule and output rule” and the like. Morespecifically, if the current time point is in the rule-fixed period atstep Sa30 in FIG. 44, the voice control section 109D decides tosynthesize voice by applying a pitch rule and an output rule having beenset in the evaluation period preceding the rule-fixed period. If, on theother hand, the current time point is in the evaluation period at stepSa31, the voice control section 109D selects any one of three pitchrules, selects any one of a total of three output rules that are: theoutput rule having been set in the evaluation period preceding therule-fixed period; and two output rules immediately upper and lower than(i.e., sandwiching in the vertical or up-down direction) the set outputpitch in the index table (see FIG. 46), and applies the thus-selectedpitch rule and output rule. At step Sa32, the voice control section 109Dhaving been supplied with pitch data instructs the voice synthesissection 112 to synthesize voice of a reply to a remark such that thepitch of the word ending of the reply assumes a relationship with thepitch indicated by the supplied pitch data as determined by the appliedpitch rule, and such that a time interval from the word ending of theremark to a time point when output of the reply is started coincideswith the time interval determined by the applied output rule.

Further, in order to update the two index tables, the voice controlsection 109D identifies, at steps Sb24 and Sb26 of FIG. 45, the pitchrule and the output rule applied to the voice synthesis of the reply andincrements, at step Sb25, each of the two items of the applied pitchrule and the two items of the applied output rule by “1”. At step Sb27,the voice control section 109D increments only the number ofapplications of the applied pitch rule by “1” and increments only thenumber of applications of the applied output rule by “1”. If the currenttime point is the end timing of the evaluation period, the voice controlsection 109D sets, at step Sb29, one of the pitch rules and one of theoutput rules which have achieved the liveliest dialogue in theevaluation period. After that, at step Sb30, the voice control section109D clears the items of pitch rules and the output rules evaluated inthe evaluation period.

With the twelfth embodiment, one of the pitch rules and one of theoutput rules which have achieved the liveliest dialogue in theevaluation period are applied in the rule-fixed period following theevaluation period, a reply of a good impression comfortable to the usercan be returned with such a pause that facilitates the user to make aremark. For example, in a case where the voice synthesis apparatus 10outputs a reply “hare desu” (romanized Japanese meaning “It'll befine.”) in response to a user's remark “asu no tenki wa?” (romanizedJapanese meaning “How will the weather be tomorrow?” as shown in FIG.17(a), a time interval Ta from the word ending “wa” (romanized Japanese)of the user's remark to the word beginning “ha” (romanized Japanese) isset at such a time interval that facilitates the user W to liven up thedialogue. In this case, the pitch of the word ending “su” (romanizedJapanese) of the reply is set in the relationship designated by thepitch rule, which can facilitate livening-up of the dialogue, withrespect to the word ending “wa” (romanized Japanese) of the user'sremark, although not particularly shown.

In the twelfth embodiment, as set forth above, voice of the reply issynthesized in such a manner that the pitch of the word ending of thereply assumes a consonant interval relationship with the pitch of theword ending of the remark as in the eleventh embodiment. Also, thetwelfth embodiment synthesizes the voice of the reply with a pause thatallows the user to make a remark more easily than the eleventhembodiment, and thus, the twelfth embodiment can make the dialogue withthe user livelier than the eleventh embodiment.

Whereas the twelfth embodiment has been described above as constructedto control a “pause” from a remark to a reply in addition to performingthe pitch control of the reply in the same manner as in the eleventhembodiment, it may be constructed to control the pause alone withoutperforming the pitch control of the reply. Content of such amodification where the pause control is performed without the pitchcontrol being performed is generally similar to the process of FIG. 45,except that “pitch rule” in FIG. 45 should be read as “output rule”, andthe content of this modification may be sufficiently understood bypersons skilled in the art from the above description of the twelfthembodiment.

<Thirteenth Embodiment>

The following describe a thirteenth embodiment of the present invention.First, a premise of the thirteenth embodiment will be briefed. A pitchrelationship in which the pitch of the word ending of a reply to aremark is felt comfortable and the like with respect to the pitch of theword ending of the remark differs from one person to another.Particularly, because the female and the male greatly differ from eachother in pitch of their remarks (i.e., the pitch of the female isgenerally lower than the pitch of the male), remarks of the female andthe male may give greatly different impressions. Further, in recentyears, a reply can sometimes be output in voice of a virtual characterof a predetermined sex and age through voice synthesis. It is consideredthat, if voice of a character replying to a remark is changed andparticularly if the sex of the character is changed, the user will havean impression different from the impression that was being receivedbefore the change. Therefore, the third embodiment of the presentinvention assumes, as various scenes, combinations of the sexes (femaleand male) of the users and the sexes of voice to be synthesized andprovides index tables for the individual scenes so that any one of theindex tables corresponding to a user's remark can be used.

FIG. 47 shows examples of the index tables which are provided in thethirteenth embodiment in corresponding relation to the combinations ofthe sexes of the users and the sexes of voice to be synthesized. Morespecifically, a total of four index tables are prepared in the managingdatabase 127 in corresponding relation to the two, i.e. female and male,sexes of the users and the two, i.e. female and male, sexes of thereplying voice synthesized by the apparatus. The voice control section109D selects any one of the four index tables in the following manner.

Namely, the voice control section 109D identifies the sex of the user,for example, from personal information of the user having logged in tothe terminal apparatus functioning as the voice synthesis apparatus 10.Alternatively, the voice control section 109D may perform volumeanalysis and frequency analysis on the user's remark, compare theanalyzed volume and frequency of the user's remark against prestoredpatterns of the female and male and identify, as the sex of the user,the sex of one of the prestored patterns that has a high similarity tothe volume and frequency of the user's remark. Further, the voicecontrol section 109D identifies the sex of the reply from setinformation (sex information of a dialogue agent). Once the voicecontrol section 109D identifies the sex of the user and the sex of thevoice of the reply in the aforementioned manner, it selects one of theindex tables that corresponds to the combination of the identifiedsexes. After the selection of the index table, rule-fixed periods andevaluation periods are repeated alternately in the instant embodiment inthe same manner as in the eleventh embodiment.

According to the thirteenth embodiment, one of the index tablescorresponding a scene of the user's remark is used, but also the pitchof the word ending of the reply is controlled, in the rule-fixed period,to assume a predetermined relationship, designated by a pitch rule setin the one index table, with respect to the pitch of the pitch of theword ending of the remark. Further, one of the pitch rules of the indextable which has achieved the liveliest dialogue is set in the evaluationperiod. Thus, the thirteenth embodiment can easily make dialogues livelyand comfortable to the users in various scenes.

The eleventh embodiment, where the rule-fixed periods and the evaluationperiods are repeated, can also converge to conditions that can readilymake dialogues comfortable to users and lively irrespective of changesin scene. However, it is expected that a time required to achieve suchconvergence (i.e., the number of repetition of the rule-fixed periodsand the evaluation periods required to achieve such convergence) wouldundesirably increase. By contrast, the thirteenth embodiment cansignificantly reduce the time required to converge to conditions thatcan readily make dialogues comfortable, if appropriate pitch rules arepreset as an initial state per scene.

Whereas the third embodiment has been described above in relation to thecase where the pitch rules as used in the eleventh embodiment are usedas the index tables, the output rules of the twelfth embodiment too maybe used in the thirteenth embodiment in combination with the pitch rulesin such a manner that switching is made between the output rules inresponse to a change in scene. Further, the scenes may comprisecombinations of the sexes and ages rather than the sexes alone.Furthermore, speeds of remarks, speeds of replies and applications ofthe voice synthesis apparatus 10, such as applications to voice guidancein various facilities like museums, art museums and zoos andapplications to voice dialogues, may be assumed and prepared as thescenes, without the scenes being limited to the sexes and ages of theusers and virtual characters replying to the users.

<Modification Using Voice Waveform Data>

Like the above-described other embodiments, the eleventh to thirteenthembodiments may be modified in a similar manner to the above-describedsecond embodiment Namely, the combination of the reply creation section110 of FIG. 41 and the voice synthesis section 112 (i.e., the voicegeneration section using the voice synthesis technique) may be replacedwith the combination of the replying voice output section 113 and thepost-processing section 114 as shown in FIG. 8 or 16 or 19 (i.e., thevoice generation section using waveform data), and voice waveform datafor example in the WAV format may be output from the replying voiceoutput section 113.

Note that the various application examples and/or the modificationsrelated to the first and second embodiments are also applicable to theeleventh to thirteenth embodiments of the present invention.

In short, the above-described eleventh to thirteenth embodiments arecharacterized in that the voice generation section (i.e., the voicesynthesis section 112 or the combination of the replying voice outputsection 113 and the post-processing section 114) is constructed toassociate the pitch of the second segment with the analyzed pitch of thefirst segment in accordance with a given rule, and in that theembodiments further includes the control section (voice control section109D) that updates the rule on the basis of reception, via the voiceinput section (102), of voice of a further remark after sounding oraudible generation of the reply.

<Fourteenth Embodiments>

The following describe, with reference to FIGS. 48 and 49, acoding/decoding device and a voice synthesis system constructed inaccordance with a fourteenth embodiment of the present invention. Thefourteenth embodiment is characterized in that voice of back-channelfeedback (simple reply) responsive to an input remark is generatedefficiently through prompt processing by the coding/decoding device 200while voice of a reply having a relatively complicated linguisticmeaning responsive to an input remark is generated efficiently throughlarge-capacity centralized processing by a computer 160. In this way,the fourteenth embodiment provides the voice synthesis system (voicesynthesis apparatus 100) capable of realizing a flexible human-machinedialogue function.

FIG. 48 is a diagram showing a hardware setup of the voice synthesisapparatus 100 (voice synthesis system) including the coding/decodingdevice constructed in accordance with the fourteenth embodiment of thepresent invention. This voice synthesis apparatus 100 (voice synthesissystem), which is for example in the form of a terminal apparatus like aportable phone, includes: the voice input section 102; the speaker 142;the coding/decoding device (hereinafter referred to as “CODEC” (coderdecoder)) 200; and the host computer 160 that is a higher-rank computeras viewed from the CODEC 200.

The CODEC 200, which is in the form of a one-chip or multi-chip module,includes a microprocessor 202, a memory 204, an A/D converter 206, and aD/A converter 208. Further, the CODEC 200 is constructed to process avoice signal by the microprocessor 202 executing a program P1 (firmware)stored in the memory 204.

The host computer 160 includes a CPU (Central Processing Unit) 162 and amemory 164. The CPU 162 is connected to the CODEC 200 and the memory 164via a bus BUS. A program P2 for voice processing in the instantembodiment as well as an operating system is stored in the memory 164.The voice processing in the instant embodiment includes a dialogueprocess for, when the user has made a remark, outputting a reply orback-channel feedback to the remark by means of synthesized voice, avoice recognition process for converting a user's remark into acharacter train, and a reproduction (playback) process for reproducingand outputting music, voice, etc. processed by the host 160.

Although not particularly shown, the voice synthesis apparatus 100 alsoincludes a display section, an operation input section, etc., so thatthe user can check states of the voice synthesis apparatus 100 and inputvarious operations to the apparatus 100. Further, the voice synthesisapparatus 100 may be in the form of a notebook or tablet personalcomputer rather than a terminal apparatus like a portable phone.

FIG. 49 is a functional block diagram showing functional arrangements ofthe voice synthesis apparatus 100 of the present invention. Thefunctional blocks are built by the microprocessor 202 executing theprogram P1 in the CODEC 200 and by the CPU 162 executing the program P2in the host 160. As shown in the figure, the CODEC 200 has built thereina pitch analysis section 106, a linguistic analysis section 108 a, acooperation section 140, a readout section 142, a back-channel feedbackdata storage section 143 and a pitch control section 144, and the host160 has built therein a linguistic analysis section 108 b, a cooperationsection 180, a reply creation section 110, a linguistic database 122, areply database 124 and a voice library 128. Blocks in FIG. 49 thatimplement substantially the same functions as those in FIG. 1 aredepicted by the same reference characters as in FIG. 1 and will not bedescribed to avoid unnecessary duplication.

The pitch analysis section 106 and the linguistic analysis section 108 ain the CODEC 200 function in substantially the same way as the pitchanalysis section 106 and the linguistic analysis section 108 shown inFIG. 1. Note, however, the linguistic analysis section 108 a determineswhether a remark received via the voice input section 102 is of contentto which back-channel feedback should be returned or of content to whichanother reply than back-channel feedback should be returned. Amongpossible examples of a specific way for the linguistic analysis section108 a to make such a determination is one where volume and pitchvariation patterns toward the word endings of, for example, typicalquestions (i.e., remarks to which replies other than back-channelfeedback are to be returned) are prestored. In this case, if pitchvariation and volume variation represented respectively by a volumewaveform and a pitch variation output from the pitch analysis section106 match (or have a high similarity to) any of the prestored volume andpitch variation patterns, the remark is determined to be a question. If,on the other hand, the pitch variation and volume variation representedrespectively by the volume waveform and the pitch variation output fromthe pitch analysis section 106 do not match (or have a low similarityto) any of the prestored volume and pitch variation patterns, the remarkis determined to be one to which back-channel should be returned. Notethat, if the linguistic analysis section 108 a is unable to determinewhether back-channel feedback should be returned or another replyback-channel feedback should be returned, or if the result of thedetermination by the linguistic analysis section 108 a has a lowreliability, a particular rule may be employed which causes thedetermination to be daringly entrusted to the host 160 (linguisticanalysis section 108 b) provided at the succeeding stage. Further,because back-channel feedback is intended to merely smooth aconversation (or improve the rhythm of the conversation) and the meaningof the back-channel feedback may be made light of, it practicallydoesn't matter so much even when back-channel feedback has been returnedalthough the remark is a question.

If it has been determined that the remark received via the voice inputsection 102 is of content to which back-channel feedback should bereturned, the cooperation section 140 controls the pitch control section144 to select back-channel data as an object of processing but alsoinforms the host 160 that the host 160 need not perform processing onthe remark. In the case where it has been determined that the remarkreceived via the voice input section 102 is of content to which anotherreply than back-channel feedback should be returned (under applicationof the particular rule, including a case where the content of the remarkis unrecognizable and a case where the result of the determination has alow reliability), the cooperation section 140 instructs the pitchcontrol section 144 to select, as an object of pitch control processing,reply data (i.e., response data other than back-channel feedback data)created by the reply creation section 110 of the host 160, but alsoinforms the host 160 that the host 160 should create (or acquire) areply (response) to the remark.

The back-channel feedback data storage section 143 stores therein aplurality of sets of back-channel feedback data. Here, the plurality ofsets of back-channel feedback data are a plurality of sets of voicewaveform data containing brief replies like “êto” (“Let me see.”), “naruhodo” (“1 see.”), “sou desune” (“Well, . . . ”)”, “a hai” (“Oh, yes.”),“nn” (“Let's see.”). The sets of voice waveform data are, for example,in the WAV format.

If it has been determined by the voice input section 102 that the remarkreceived via the voice input section 102 is of content to whichback-channel feedback should be returned, the readout section 142 readsout any one of the sets of back-channel feedback data in accordance witha predetermined order or randomly and supplies the read-out back-channelfeedback data to the pitch control section 144. With such a constructionwhere the back-channel feedback data is output independently of thespecific content of the remark, back-channel feedback irrelevant to theremark may sometimes be output, which, however, does not matter so muchbecause the meaning of the back-channel feedback can be made light of asnoted above.

Because the back-channel feedback read out by the readout section 142and the reply data (response data other than back-channel feedback)supplied by the reply creation section 182 are each voice waveform data,the back-channel feedback and the reply (response other thanback-channel feedback) can be output in voice by the back-channelfeedback and the response data being reproduced as-is. However, thefourteenth embodiment is constructed to control the pitch of theback-channel feedback or reply (response) in consideration of the pitchof the remark (question) to which the back-channel feedback or reply isto be returned as in the above-described first embodiment etc., and sucha pitch control function is performed by the pitch control section 144.Namely, like in the above-described first embodiment etc., the pitchcontrol section 144 controls the pitches of voice, based on theback-channel feedback data read out from the back-channel feedback datastorage section 143 or the reply data supplied from the reply creationsection 110, in accordance with the pitch of the first segment (e.g.,word ending) of the remark analyzed by the pitch analysis section 106.More specifically, the pitch control section 144 controls the replyingvoice synthesis by controlling the pitches of the entire replying voiceof the back-channel feedback or reply so that the pitch of a particularsegment (second segment) of the back-channel feedback data or aparticular segment (third segment) of the reply data assumes apredetermined interval relationship with the pitch of the first segmentof the remark. A replying voice signal synthesized by the pitch controlsection 144 is converted into an analogue signal by the D/A converter208 and then audibly output via the speaker 142.

In the host 160, on the other hand, the cooperation section 180 suppliesinformation, such as various parameters and various states, to thecooperation section 140 of the CODEC 200. Further, when a request forcreating a reply (response) has been received from the cooperationsection 140, the cooperation section 180 controls the linguisticanalysis section 108 b and the reply creation section 110. Like thelinguistic analysis section 108 of FIG. 1, the linguistic analysissection 108 b analyzes the meaning of the remark represented by thevoice signal converted into a digital signal by the A/D converter 206.In the host 160 shown in FIG. 49, the linguistic analysis section 108 band the reply creation section 110 function substantially similarly tothe linguistic analysis section 108 and the reply creation section 110shown in FIG. 1. Note that the reply creation section 110 in the host160 of FIG. 49 is constructed, in principle, to create a reply(response) other than back-channel feedback. However, if the linguisticanalysis section 108 a in the CODEC 200 is unable to recognize thecontent of the remark, or if the result of the recognition by thelinguistic analysis section 108 a has a low reliability, then the replycreation section 110 in the host 160 sometimes create back-channelfeedback as a reply to the remark. Reply data created or acquired by thereply creation section 110 is supplied to the pitch control section 144.

The following describe behavior of the voice synthesis apparatus 100.FIG. 50 is a flow chart of voice processing performed in the voicesynthesis apparatus 100. First, in response to the user performing apredetermined operation, e.g. selecting on a main menu (not shown) anicon corresponding to the voice processing, the CPU 162 starts up theprogram P2, so that the functional blocks shown in FIG. 49 are built inthe CODEC 200 and the host 160.

Once the user inputs voice of a remark to the voice input section 102,the voice is converted into a voice signal by the voice input section102 and then converted into a digital signal by means of the A/Dconverter 206, at step S11. Then, at step S12, the cooperation section180 in the host 160 determines whether execution of a dialogue processis designated in the started voice processing. If the execution of thedialogue process is not designated in the started voice processing (Nodetermination at step S12), other processes are performed at step S16.Examples of the other processes include: a voice recognition process forsupplying the voice signal, converted into the digital signal, toanother functional block (not shown) in the host 160, as indicated by 1in FIG. 49, so that the other functional block converts the user'sremark into a character train; and a reproduction process for convertingthe data processed by the other block into an analog signal by means ofthe D/A converter 208 and audibly reproducing the analog signal throughthe speaker 142.

If, on the other hand, the execution of the dialogue process isdesignated in the started voice processing (Yes determination at stepS12), the cooperation section 180 informs the cooperation section 140 ofthe CODEC 200 to that effect, so that the cooperation section 140instructs the linguistic analysis section 108 a to determine at step S13whether the input remark is of content to which back-channel feedbackshould be returned. If the input remark is of content to whichback-channel feedback should be returned (Yes determination at stepS13), a back-channel feedback process is performed as follows at stepS14. If, on the other hand, the input remark is not of content to whichback-channel feedback should be returned (No determination at step S13),a reply process is performed as follows at step S15. Note that theinstant voice processing is brought to an end after steps S14, S15 andS16.

FIG. 51 is a flow chart showing details of the back-channel feedbackprocess performed at step S14. First, the linguistic analysis section108 a having determined that the input remark is of content to whichback-channel feedback should be returned informs the cooperation section140 to that effect, and the cooperation section 140 informs thecooperation section 180 of the host 160 that creation of a reply to theremark is unnecessary (step Sa41). Upon receipt of such information fromthe cooperation section 140, the cooperation section 180 instructs thelinguistic analysis section 108 b to ignore the digital signalcorresponding to the remark. Thus, the voice signal on the remark is notperformed in the host 160 (step Sb31).

Meanwhile, the pitch analysis section 106 analyzes the voice signal ofthe input remark for example in the following manner to thereby identifythe pitch of the first segment (e.g., the word ending) of the remark andthen supplies pitch data indicative of the identified pitch to the pitchcontrol section 144, at step Sa42. In parallel with the pitch analysis,the readout section 142 selectively reads out any one of the sets ofback-channel feedback data stored in the back-channel feedback datastorage section 143 and supplies the read-out back-channel feedback datato the pitch control section 144, at step Sa43. Like in theabove-described embodiments, the pitch control section 144 analyzes thepitch of a portion of the simply-reproduced back-channel feedback datacorresponding to the second segment (e.g., word ending), then shifts thepitches of the entire back-channel feedback data in such a manner thatthe analyzed pitch assumes a predetermined interval (e.g., five degreesdown) relationship with the pitch (pitch of the first segment such asthe word ending) indicated by the pitch data supplied from the pitchanalysis section 106, and then outputs the pitch-shifted back-channelfeedback data (step Sa44). The pitch control section 144 reproduces thepitch-shifted back-channel feedback data and supplies the reproducedpitch-shifted back-channel feedback data to the D/A converter 208. Inthis manner, the back-channel feedback pitch shifted in correspondencewith the remark is output. After the output of the pitch-shiftedback-channel feedback data, the voice processing (FIG. 50) is brought toan end together with the back-channel feedback process.

The following describe the reply process performed at step S15 of thevoice processing. FIG. 52 is a flow chart showing details of the replyprocess. The linguistic analysis section 108 a, having determined thatthe input remark is of content to which back-channel feedback should notbe returned, informs the cooperation section 140 to that effect, so thatthe cooperation section 140 notifies the cooperation section 180 of thehost 160 that a reply to the remark should be created (reply request)(step Sa45). Upon receipt of such a notification, the cooperationsection 180 instructs the linguistic analysis section 108 b to analyzethe meaning of the remark. Then, the linguistic analysis section 108 banalyze the meaning of the remark as instructed at step Sb32. Then, thereply creation section 110 creates (acquires) reply data correspondingto the meaning of the remark and supplies the reply data to the pitchcontrol section 144 at step Sb33.

Meanwhile, in the reply process, the pitch analysis section 106identifies a pitch of the first segment (e.g., word ending) of the inputremark and then supplies pitch data indicative of the identified pitchto the pitch control section 144 at step Sa46, in the same manner as atstep Sa42 above. Then, the pitch control section 144 analyzes a pitch ofa third segment (e.g., word ending) of the reply data when the replydata is reproduced simply but also shifts pitches of the entire replydata so that the analyzed pitch assumes a five-degree-down relationshipwith the pitch indicated by the pitch data supplied from the pitchanalysis section 106, and then the pitch control section 144 outputs thepitch-shifted reply data (step Sa47).

With such an embodiment of the voice synthesis apparatus 100, it ispossible to give the user a natural feel as if a dialog were beingconducted between persons, irrespective of whether back-channel feedbackis output with back-channel feedback data or another reply thanback-channel feedback is output with reply data. Further, according tothe instant embodiment, when back-channel feedback is to be returned tothe remark, the back-channel feedback data is processed in the CODEC 200alone without being processed in the host 160, and thus, it is possibleto output the back-channel feedback promptly with a good response.Further, when another reply than back-channel feedback is to be outputin response to the remark, such a reply is created or acquired in thehost 160, so that an increased accuracy of the reply can be achieved.Therefore, the instant embodiment not only allows the back-channelfeedback to be output promptly with a good response but also allows theother reply than back-channel feedback to be output with an increasedaccuracy.

<Remark and Bach-Channel Feedback>

The fourteenth embodiment has been described as constructed in such amanner that any one of the sets of back-channel feedback data stored inthe back-channel feedback data storage section 143 is read out when ithas been determined that the remark is of content to which back-channelfeedback data should be returned. With such a construction, however,back-channel feedback irrelevant to the remark may sometimes be outputalthough it does not matter so much, as noted above. Thus, sets ofback-channel feedback data may be associated in advance with typicalvolume and pitch variation patterns of possible remarks corresponding tothe back-channel feedback, so that, when the linguistic analysis section108 a has determined that volume and pitch variation of a remarksupplied from the pitch analysis section 106 matches the volume andpitch variation patterns of any one of the remarks, it instructs thereadout section 142 to read out the set of back-channel feedback dataassociated with that remark. More specifically, with such aconstruction, if a set of back-channel feedback data of “sou desune”(“Right.”) is prestored in the back-channel feedback data storagesection 143 in association with volume and pitch variation of a remark“samui ni” (It is cold, isn't it?), and if volume and pitch variation ofa user's actual remark “samui ni” (It is cold, isn't it?) matches thestored volume and pitch variation of the remark “samui nâ”, thenappropriate back-channel feedback “Right.” can be output. Thus, in thiscase, inappropriate or irrelevant back-channel feedback like “êto” (“Letme see.”), “naru hodo” (“I see.”) or “sorede” (“So what?”) can beavoided from being output.

<Linguistic Analysis Section>

Whereas the fourteenth embodiment has been described above in relationto the case where the CODEC 200 includes the linguistic analysis section108 a and the host 160 includes the linguistic analysis section 108 b,any one of the linguistic analysis sections, such as the linguisticanalysis section 108 a, may be dispensed with. If the linguisticanalysis section 108 a is dispensed with, the linguistic analysissection 108 b performs the function of the linguistic analysis section108 a. Namely, if the linguistic analysis section 108 b determineswhether the remark represented by the digital voice signal is of contentto which back-channel feedback should be returned. If the remark is ofcontent to which back-channel feedback should be returned, thelinguistic analysis section 108 b may supply information to that effectto the readout section 142 of the CODEC 200 directly or indirectly viathe cooperation sections 180 and 140 and instruct the readout section142 to read out back-channel feedback data.

To summarize the primary constructional features of the CODEC(coding/decoding device) 200, the CODEC 200 includes: the A/D converter(206) that converts an input voice signal of a remark into a digitalsignal; the pitch analysis section (106) that analyzes the pitch of thefirst segment of the remark on the basis of the digital signal; aback-channel feedback acquisition section (combination of the linguisticanalysis section 108 a, the readout section 142 and the back-channeldata storage section 143) that, when back-channel feedback is to bereturned to the remark, acquires back-channel feedback datacorresponding to the meaning of the remark; the pitch control section(144) that controls the pitch of the acquired back-channel feedback datain such a manner that the second segment of the back-channel feedbackdata has a pitch associated with the analyzed pitch of the firstsegment; and the D/A converter (208) constructed to convert thepitch-controlled back-channel feedback data into an analogue signal.

Note that the various application examples and/or the modificationsrelated to the first and second embodiments are also applicable to thefourteenth embodiment of the present invention.

Further, the primary functional features of the host computer 160 may besummarized as follows. When replying voice other than the back-channelfeedback should be returned to the remark, the host computer 160 isconstructed to acquire replying voice data responsive to the remark inaccordance with the digital signal converted by the A/D converter (206)and then return the acquired replying voice data to the coding/decodingdevice (CODEC 200). The pitch control section (144) of thecoding/decoding device (CODEC 200) is further constructed to control thepitch of the replying voice data, returned from the host computer (160),so that the third segment of the replying voice data has a pitchassociated with the analyzed pitch of the first segment, and the D/Aconverter (208) is further constructed to convert the pitch-controlledreplying voice data into an analogue signal.

What is claimed is:
 1. A voice synthesis apparatus comprising: a voiceinput section configured to receive a voice signal of a remark; a pitchanalysis section configured to analyze a pitch of a first segment of theremark, wherein the first segment is a word ending of the remark; anacquisition section configured to acquire a reply to the remark; and avoice generation section configured to generate voice of the replyacquired by said acquisition section, said voice generation sectionshifting pitches of the entire voice waveform data of the reply by asame amount so that a second segment of the reply has a pitch associatedwith the pitch of the first segment analyzed by said pitch analysissection, wherein the second segment is a word beginning or word endingof the reply.
 2. The voice synthesis apparatus as claimed in claim 1,wherein the remark is a question, and the reply corresponds to thequestion.
 3. The voice synthesis apparatus as claimed in claim 1,wherein said voice generation section is configured to provisionally setthe pitch of the second segment of the reply at the pitch associatedwith the pitch of the first segment, and wherein said voice generationsection is further configured to perform at least one of: an operationof, if the provisionally-set pitch of the second segment is lower than apredetermined first threshold value, shifting the provisionally-setpitch of the second segment to a pitch one octave up; and an operationof, if the provisionally-set pitch of the second segment is higher thana predetermined second threshold value, shifting the provisionally-setpitch of the second segment to a pitch one octave down.
 4. The voicesynthesis apparatus as claimed in claim 1, wherein said voice generationsection is configured to provisionally set the pitch of the secondsegment of the reply at the pitch associated with the pitch of the firstsegment, and wherein said voice generation section is further configuredto shift the provisionally-set pitch to a pitch one octave up or down inaccordance with a designated attribute.
 5. The voice synthesis apparatusas claimed in claim 1, wherein any one of a first mode and a second modeis settable as an operation mode of said voice generation section,wherein, in said first mode, said voice generation section is configuredto shift the pitches of the entire voice waveform data of the reply insuch a manner that the interval of the pitch of said second segmentrelative to the pitch of said first segment becomes a consonantinterval, and wherein, in said second mode, said voice generationsection is configured to shift the pitches of the entire voice waveformdata of the reply in such a manner that the interval of the pitch ofsaid second segment relative to the pitch of said first segment becomesa dissonant interval.
 6. The voice synthesis apparatus as claimed inclaim 1, further comprising: a non-linguistic analysis sectionconfigured to analyze non-linguistic information, other than pitch,related to the remark; and a control section configured to control voicegeneration, in said voice generation section, of the reply in accordancewith the analyzed non-linguistic information.
 7. The voice synthesisapparatus as claimed in claim 1, further comprising: a linguisticanalysis section configured to analyze linguistic information includedin the remark and the reply; and a control section configured to controlvoice generation, in said voice generation section, of the reply inaccordance with the analyzed linguistic information.
 8. The voicesynthesis apparatus as claimed in claim 1, further comprising: anon-linguistic analysis section configured to analyze pitch variation inthe remark; and a control section configured to control the pitches ofthe entire voice waveform data of the reply, generated in said voicegeneration section, to vary in accordance with the pitch variation inthe remark.
 9. The voice synthesis apparatus as claimed in claim 1,wherein said voice generation section is configured to associate thepitch of said second segment with the pitch of said first segment inaccordance with a given rule and generate voice with a characteristicbased on a given agent attribute, the voice synthesis apparatus furthercomprising: a control section configured to determine the rule based onat least one of an agent attribute and an attribute of a speaker of theremark.
 10. The voice synthesis apparatus as claimed in claim 1, whereinsaid voice generation section is configured to associate the pitch ofsaid second segment with the pitch of said first segment in accordancewith a given rule, the voice synthesis apparatus further comprising: acontrol section configured to update the rule based on receiving voiceof a further remark via said voice input section after sounding of thevoice of the reply.
 11. The voice synthesis apparatus as claimed inclaim 1, wherein said voice generation section is configured to shiftthe pitches of the entire voice waveform data of the reply in such amanner that an interval of the pitch of said second segment relative tothe pitch of said first segment becomes a consonant interval.
 12. Thevoice synthesis apparatus as claimed in claim 11, wherein said voicegeneration section is configured to shift the pitches of the entirevoice waveform data of the reply in such a manner that the interval ofthe pitch of said second segment relative to the pitch of said firstsegment becomes a consonant interval of five degrees lower than thepitch of said first segment.
 13. A computer-implemented methodcomprising: receiving a voice signal of a remark; analyzing a pitch of afirst segment of the remark, wherein the first segment is a word endingof the remark; acquiring a reply to the remark; synthesizing voice ofthe acquired reply; and shifting pitches of the entire voice waveformdata of the reply by a same amount so that a pitch of a second segmentof the voice of the reply has a pitch associated with the analyzed pitchof the first segment, wherein the second segment is a word beginning orword ending of the reply.
 14. A coding/decoding device comprising: anA/D converter configured to convert an input voice signal of a remarkinto a digital signal; a pitch analysis section configured to analyze apitch of a first segment of the remark based on the digital signal,wherein the first segment is a word ending of the remark; a back-channelfeedback acquisition section configured to, when back-channel feedbackis to be returned to the remark, acquire back-channel feedback datacorresponding to a meaning of the remark; a pitch control sectionconfigured to shift pitches of the entire back-channel feedback data bya same amount so that a second segment of the back-channel feedback datahas a pitch associated with the analyzed pitch of the first segment,wherein the second segment is a word beginning or word ending of theback-channel feedback data; and a D/A converter configured to convertthe pitch-shifted back-channel feedback data into an analog signal. 15.The coding/decoding device as claimed in claim 14, wherein the digitalsignal converted by the A/D converter is supplied to a host computer,wherein the pitch control section is further configured to receivereplying voice data, responsive to the remark, returned from the hostcomputer and shift pitches of the replying voice data by a same amountso that a third segment of the received replying voice data has a pitchassociated with the analyzed pitch of the first segment, and wherein theD/A converter is further configured to convert the pitch-shiftedreplying voice data, into an analog signal.
 16. A voice synthesis systemcomprising a coding/decoding device and a host computer, saidcoding/decoding device comprising: an A/D converter configured toconvert an input voice signal of a remark into a digital signal; a pitchanalysis section configured to analyze a pitch of a first segment of theremark based on the digital signal, wherein the first segment is a wordending of the remark; a back-channel feedback acquisition sectionconfigured to, when back-channel feedback is to be returned to theremark, acquire back-channel feedback data corresponding to a meaning ofthe remark; a pitch control section configured to shift pitches of theentire back-channel feedback data by a same amount so that a secondsegment of the back-channel feedback data has a pitch associated withthe analyzed pitch of the first segment, wherein the second segment is aword beginning or word ending of the back-channel feedback data; and aD/A converter configured to convert the pitch-shifted back-channelfeedback data into an analog signal, wherein said host computer isconfigured to, when replying voice other than the back-channel feedbackis to be returned to the remark, acquire replying voice data, responsiveto the remark, in accordance with the digital signal converted by saidA/D converter and return the acquired replying voice data to saidcoding/decoding device, wherein said pitch control section is furtherconfigured to shift pitches of the replying voice data by a same amountso that a third segment of the replying voice data returned from thehost computer has a pitch associated with the analyzed pitch of thefirst segment, and wherein said D/A converter is further configured toconvert the pitch-shifted replying voice data, into an analog signal.17. A method comprising: converting, by means of an A/D converter, aninput voice signal of a remark into a digital signal; analyzing, bymeans of a processor, a pitch of a first segment of the remark based onthe digital signal, wherein the first segment is a word ending of theremark; acquiring, by means of the processor, back-channel feedback datacorresponding to a meaning of the remark, when back-channel feedback isto be returned to the remark; shifting, by means of the processor,pitches of the entire back-channel feedback data by a same amount sothat a second segment of the back-channel feedback data has a pitchassociated with the analyzed pitch of the first segment, wherein thesecond segment is a word beginning or word ending of the back-channelfeedback data; and converting, by means of a D/A converter, thepitch-shifted back-channel feedback data into an analog signal.